[3320] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Utility routines.
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| 4 | *
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| 5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 8 | */
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| 9 | #include "libbb.h"
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| 10 |
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| 11 | #define ZIPPED (ENABLE_FEATURE_SEAMLESS_LZMA \
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| 12 | || ENABLE_FEATURE_SEAMLESS_BZ2 \
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| 13 | || ENABLE_FEATURE_SEAMLESS_GZ \
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| 14 | /* || ENABLE_FEATURE_SEAMLESS_Z */ \
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| 15 | )
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| 16 |
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| 17 | #if ZIPPED
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| 18 | # include "archive.h"
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| 19 | #endif
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| 20 |
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| 21 |
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| 22 | /* Suppose that you are a shell. You start child processes.
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| 23 | * They work and eventually exit. You want to get user input.
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| 24 | * You read stdin. But what happens if last child switched
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| 25 | * its stdin into O_NONBLOCK mode?
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| 26 | *
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| 27 | * *** SURPRISE! It will affect the parent too! ***
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| 28 | * *** BIG SURPRISE! It stays even after child exits! ***
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| 29 | *
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| 30 | * This is a design bug in UNIX API.
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| 31 | * fcntl(0, F_SETFL, fcntl(0, F_GETFL) | O_NONBLOCK);
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| 32 | * will set nonblocking mode not only on _your_ stdin, but
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| 33 | * also on stdin of your parent, etc.
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| 34 | *
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| 35 | * In general,
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| 36 | * fd2 = dup(fd1);
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| 37 | * fcntl(fd2, F_SETFL, fcntl(fd2, F_GETFL) | O_NONBLOCK);
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| 38 | * sets both fd1 and fd2 to O_NONBLOCK. This includes cases
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| 39 | * where duping is done implicitly by fork() etc.
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| 40 | *
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| 41 | * We need
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| 42 | * fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD) | O_NONBLOCK);
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| 43 | * (note SETFD, not SETFL!) but such thing doesn't exist.
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| 44 | *
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| 45 | * Alternatively, we need nonblocking_read(fd, ...) which doesn't
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| 46 | * require O_NONBLOCK dance at all. Actually, it exists:
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| 47 | * n = recv(fd, buf, len, MSG_DONTWAIT);
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| 48 | * "MSG_DONTWAIT:
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| 49 | * Enables non-blocking operation; if the operation
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| 50 | * would block, EAGAIN is returned."
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| 51 | * but recv() works only for sockets!
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| 52 | *
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| 53 | * So far I don't see any good solution, I can only propose
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| 54 | * that affected readers should be careful and use this routine,
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| 55 | * which detects EAGAIN and uses poll() to wait on the fd.
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| 56 | * Thankfully, poll() doesn't care about O_NONBLOCK flag.
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| 57 | */
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| 58 | ssize_t FAST_FUNC nonblock_safe_read(int fd, void *buf, size_t count)
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| 59 | {
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| 60 | struct pollfd pfd[1];
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| 61 | ssize_t n;
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| 62 |
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| 63 | while (1) {
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| 64 | n = safe_read(fd, buf, count);
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| 65 | if (n >= 0 || errno != EAGAIN)
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| 66 | return n;
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| 67 | /* fd is in O_NONBLOCK mode. Wait using poll and repeat */
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| 68 | pfd[0].fd = fd;
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| 69 | pfd[0].events = POLLIN;
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| 70 | safe_poll(pfd, 1, -1); /* note: this pulls in printf */
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| 71 | }
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| 72 | }
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| 73 |
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| 74 | // Reads one line a-la fgets (but doesn't save terminating '\n').
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| 75 | // Reads byte-by-byte. Useful when it is important to not read ahead.
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| 76 | // Bytes are appended to pfx (which must be malloced, or NULL).
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| 77 | char* FAST_FUNC xmalloc_reads(int fd, char *buf, size_t *maxsz_p)
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| 78 | {
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| 79 | char *p;
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| 80 | size_t sz = buf ? strlen(buf) : 0;
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| 81 | size_t maxsz = maxsz_p ? *maxsz_p : (INT_MAX - 4095);
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| 82 |
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| 83 | goto jump_in;
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| 84 | while (sz < maxsz) {
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| 85 | if ((size_t)(p - buf) == sz) {
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| 86 | jump_in:
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| 87 | buf = xrealloc(buf, sz + 128);
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| 88 | p = buf + sz;
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| 89 | sz += 128;
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| 90 | }
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| 91 | /* nonblock_safe_read() because we are used by e.g. shells */
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| 92 | if (nonblock_safe_read(fd, p, 1) != 1) { /* EOF/error */
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| 93 | if (p == buf) { /* we read nothing */
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| 94 | free(buf);
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| 95 | return NULL;
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| 96 | }
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| 97 | break;
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| 98 | }
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| 99 | if (*p == '\n')
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| 100 | break;
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| 101 | p++;
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| 102 | }
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| 103 | *p = '\0';
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| 104 | if (maxsz_p)
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| 105 | *maxsz_p = p - buf;
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| 106 | p++;
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| 107 | return xrealloc(buf, p - buf);
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| 108 | }
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| 109 |
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| 110 | // Read (potentially big) files in one go. File size is estimated
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| 111 | // by stat. Extra '\0' byte is appended.
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| 112 | void* FAST_FUNC xmalloc_read(int fd, size_t *maxsz_p)
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| 113 | {
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| 114 | char *buf;
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| 115 | size_t size, rd_size, total;
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| 116 | size_t to_read;
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| 117 | struct stat st;
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| 118 |
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| 119 | to_read = maxsz_p ? *maxsz_p : (INT_MAX - 4095); /* max to read */
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| 120 |
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| 121 | /* Estimate file size */
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| 122 | st.st_size = 0; /* in case fstat fails, assume 0 */
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| 123 | fstat(fd, &st);
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| 124 | /* /proc/N/stat files report st_size 0 */
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| 125 | /* In order to make such files readable, we add small const */
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| 126 | size = (st.st_size | 0x3ff) + 1;
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| 127 |
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| 128 | total = 0;
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| 129 | buf = NULL;
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| 130 | while (1) {
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| 131 | if (to_read < size)
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| 132 | size = to_read;
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| 133 | buf = xrealloc(buf, total + size + 1);
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| 134 | rd_size = full_read(fd, buf + total, size);
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| 135 | if ((ssize_t)rd_size == (ssize_t)(-1)) { /* error */
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| 136 | free(buf);
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| 137 | return NULL;
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| 138 | }
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| 139 | total += rd_size;
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| 140 | if (rd_size < size) /* EOF */
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| 141 | break;
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| 142 | if (to_read <= rd_size)
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| 143 | break;
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| 144 | to_read -= rd_size;
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| 145 | /* grow by 1/8, but in [1k..64k] bounds */
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| 146 | size = ((total / 8) | 0x3ff) + 1;
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| 147 | if (size > 64*1024)
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| 148 | size = 64*1024;
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| 149 | }
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| 150 | buf = xrealloc(buf, total + 1);
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| 151 | buf[total] = '\0';
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| 152 |
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| 153 | if (maxsz_p)
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| 154 | *maxsz_p = total;
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| 155 | return buf;
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| 156 | }
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| 157 |
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| 158 | #ifdef USING_LSEEK_TO_GET_SIZE
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| 159 | /* Alternatively, file size can be obtained by lseek to the end.
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| 160 | * The code is slightly bigger. Retained in case fstat approach
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| 161 | * will not work for some weird cases (/proc, block devices, etc).
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| 162 | * (NB: lseek also can fail to work for some weird files) */
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| 163 |
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| 164 | // Read (potentially big) files in one go. File size is estimated by
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| 165 | // lseek to end.
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| 166 | void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
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| 167 | {
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| 168 | char *buf;
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| 169 | size_t size;
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| 170 | int fd;
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| 171 | off_t len;
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| 172 |
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| 173 | fd = open(filename, O_RDONLY);
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| 174 | if (fd < 0)
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| 175 | return NULL;
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| 176 |
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| 177 | /* /proc/N/stat files report len 0 here */
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| 178 | /* In order to make such files readable, we add small const */
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| 179 | size = 0x3ff; /* read only 1k on unseekable files */
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| 180 | len = lseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */
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| 181 | if (len != (off_t)-1) {
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| 182 | xlseek(fd, 0, SEEK_SET);
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| 183 | size = maxsz_p ? *maxsz_p : (INT_MAX - 4095);
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| 184 | if (len < size)
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| 185 | size = len;
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| 186 | }
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| 187 |
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| 188 | buf = xmalloc(size + 1);
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| 189 | size = read_close(fd, buf, size);
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| 190 | if ((ssize_t)size < 0) {
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| 191 | free(buf);
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| 192 | return NULL;
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| 193 | }
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| 194 | buf = xrealloc(buf, size + 1);
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| 195 | buf[size] = '\0';
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| 196 |
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| 197 | if (maxsz_p)
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| 198 | *maxsz_p = size;
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| 199 | return buf;
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| 200 | }
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| 201 | #endif
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| 202 |
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| 203 | // Read (potentially big) files in one go. File size is estimated
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| 204 | // by stat.
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| 205 | void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
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| 206 | {
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| 207 | char *buf;
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| 208 | int fd;
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| 209 |
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| 210 | fd = open(filename, O_RDONLY);
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| 211 | if (fd < 0)
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| 212 | return NULL;
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| 213 |
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| 214 | buf = xmalloc_read(fd, maxsz_p);
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| 215 | close(fd);
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| 216 | return buf;
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| 217 | }
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| 218 |
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| 219 | /* Die with an error message if we can't read the entire buffer. */
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| 220 | void FAST_FUNC xread(int fd, void *buf, size_t count)
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| 221 | {
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| 222 | if (count) {
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| 223 | ssize_t size = full_read(fd, buf, count);
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| 224 | if ((size_t)size != count)
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| 225 | bb_error_msg_and_die("short read");
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| 226 | }
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| 227 | }
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| 228 |
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| 229 | /* Die with an error message if we can't read one character. */
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| 230 | unsigned char FAST_FUNC xread_char(int fd)
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| 231 | {
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| 232 | char tmp;
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| 233 | xread(fd, &tmp, 1);
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| 234 | return tmp;
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| 235 | }
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| 236 |
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| 237 | void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p)
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| 238 | {
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| 239 | void *buf = xmalloc_open_read_close(filename, maxsz_p);
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| 240 | if (!buf)
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| 241 | bb_perror_msg_and_die("can't read '%s'", filename);
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| 242 | return buf;
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| 243 | }
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| 244 |
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| 245 | /* Used by e.g. rpm which gives us a fd without filename,
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| 246 | * thus we can't guess the format from filename's extension.
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| 247 | */
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| 248 | #if ZIPPED
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| 249 | void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/)
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| 250 | {
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| 251 | const int fail_if_not_detected = 1;
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| 252 | union {
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| 253 | uint8_t b[4];
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| 254 | uint16_t b16[2];
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| 255 | uint32_t b32[1];
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| 256 | } magic;
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| 257 | int offset = -2;
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| 258 | # if BB_MMU
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| 259 | IF_DESKTOP(long long) int FAST_FUNC (*xformer)(int src_fd, int dst_fd);
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| 260 | enum { xformer_prog = 0 };
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| 261 | # else
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| 262 | enum { xformer = 0 };
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| 263 | const char *xformer_prog;
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| 264 | # endif
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| 265 |
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| 266 | /* .gz and .bz2 both have 2-byte signature, and their
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| 267 | * unpack_XXX_stream wants this header skipped. */
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| 268 | xread(fd, magic.b16, sizeof(magic.b16[0]));
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| 269 | if (ENABLE_FEATURE_SEAMLESS_GZ
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| 270 | && magic.b16[0] == GZIP_MAGIC
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| 271 | ) {
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| 272 | # if BB_MMU
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| 273 | xformer = unpack_gz_stream;
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| 274 | # else
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| 275 | xformer_prog = "gunzip";
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| 276 | # endif
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| 277 | goto found_magic;
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| 278 | }
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| 279 | if (ENABLE_FEATURE_SEAMLESS_BZ2
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| 280 | && magic.b16[0] == BZIP2_MAGIC
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| 281 | ) {
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| 282 | # if BB_MMU
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| 283 | xformer = unpack_bz2_stream;
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| 284 | # else
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| 285 | xformer_prog = "bunzip2";
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| 286 | # endif
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| 287 | goto found_magic;
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| 288 | }
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| 289 | if (ENABLE_FEATURE_SEAMLESS_XZ
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| 290 | && magic.b16[0] == XZ_MAGIC1
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| 291 | ) {
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| 292 | offset = -6;
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| 293 | xread(fd, magic.b32, sizeof(magic.b32[0]));
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| 294 | if (magic.b32[0] == XZ_MAGIC2) {
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| 295 | # if BB_MMU
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| 296 | xformer = unpack_xz_stream;
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| 297 | /* unpack_xz_stream wants fd at position 6, no need to seek */
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| 298 | //xlseek(fd, offset, SEEK_CUR);
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| 299 | # else
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| 300 | xformer_prog = "unxz";
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| 301 | # endif
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| 302 | goto found_magic;
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| 303 | }
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| 304 | }
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| 305 |
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| 306 | /* No known magic seen */
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| 307 | if (fail_if_not_detected)
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| 308 | bb_error_msg_and_die("no gzip"
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| 309 | IF_FEATURE_SEAMLESS_BZ2("/bzip2")
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| 310 | IF_FEATURE_SEAMLESS_XZ("/xz")
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| 311 | " magic");
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| 312 | xlseek(fd, offset, SEEK_CUR);
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| 313 | return;
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| 314 |
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| 315 | found_magic:
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| 316 | # if !BB_MMU
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| 317 | /* NOMMU version of open_transformer execs
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| 318 | * an external unzipper that wants
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| 319 | * file position at the start of the file */
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| 320 | xlseek(fd, offset, SEEK_CUR);
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| 321 | # endif
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| 322 | open_transformer(fd, xformer, xformer_prog);
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| 323 | }
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| 324 | #endif /* ZIPPED */
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| 325 |
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| 326 | int FAST_FUNC open_zipped(const char *fname)
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| 327 | {
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| 328 | #if !ZIPPED
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| 329 | return open(fname, O_RDONLY);
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| 330 | #else
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| 331 | char *sfx;
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| 332 | int fd;
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| 333 |
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| 334 | fd = open(fname, O_RDONLY);
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| 335 | if (fd < 0)
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| 336 | return fd;
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| 337 |
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| 338 | sfx = strrchr(fname, '.');
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| 339 | if (sfx) {
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| 340 | sfx++;
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| 341 | if (ENABLE_FEATURE_SEAMLESS_LZMA && strcmp(sfx, "lzma") == 0)
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| 342 | /* .lzma has no header/signature, just trust it */
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| 343 | open_transformer(fd, unpack_lzma_stream, "unlzma");
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| 344 | else
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| 345 | if ((ENABLE_FEATURE_SEAMLESS_GZ && strcmp(sfx, "gz") == 0)
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| 346 | || (ENABLE_FEATURE_SEAMLESS_BZ2 && strcmp(sfx, "bz2") == 0)
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| 347 | || (ENABLE_FEATURE_SEAMLESS_XZ && strcmp(sfx, "xz") == 0)
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| 348 | ) {
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| 349 | setup_unzip_on_fd(fd /*, fail_if_not_detected: 1*/);
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| 350 | }
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| 351 | }
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| 352 |
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| 353 | return fd;
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| 354 | #endif
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| 355 | }
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| 356 |
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| 357 | void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
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| 358 | {
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| 359 | int fd;
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| 360 | char *image;
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| 361 |
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| 362 | fd = open_zipped(fname);
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| 363 | if (fd < 0)
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| 364 | return NULL;
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| 365 |
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| 366 | image = xmalloc_read(fd, maxsz_p);
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| 367 | if (!image)
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| 368 | bb_perror_msg("read error from '%s'", fname);
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| 369 | close(fd);
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| 370 |
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| 371 | return image;
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| 372 | }
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