[1765] | 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 tarball for details.
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| 8 | */
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| 9 |
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| 10 | #include "libbb.h"
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| 11 |
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| 12 | ssize_t safe_read(int fd, void *buf, size_t count)
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| 13 | {
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| 14 | ssize_t n;
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| 15 |
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| 16 | do {
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| 17 | n = read(fd, buf, count);
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| 18 | } while (n < 0 && errno == EINTR);
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| 19 |
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| 20 | return n;
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| 21 | }
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| 22 |
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| 23 | /*
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| 24 | * Read all of the supplied buffer from a file.
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| 25 | * This does multiple reads as necessary.
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| 26 | * Returns the amount read, or -1 on an error.
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| 27 | * A short read is returned on an end of file.
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| 28 | */
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| 29 | ssize_t full_read(int fd, void *buf, size_t len)
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| 30 | {
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| 31 | ssize_t cc;
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| 32 | ssize_t total;
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| 33 |
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| 34 | total = 0;
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| 35 |
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| 36 | while (len) {
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| 37 | cc = safe_read(fd, buf, len);
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| 38 |
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| 39 | if (cc < 0)
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| 40 | return cc; /* read() returns -1 on failure. */
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| 41 | if (cc == 0)
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| 42 | break;
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| 43 | buf = ((char *)buf) + cc;
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| 44 | total += cc;
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| 45 | len -= cc;
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| 46 | }
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| 47 |
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| 48 | return total;
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| 49 | }
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| 50 |
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| 51 | // Die with an error message if we can't read the entire buffer.
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| 52 | void xread(int fd, void *buf, size_t count)
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| 53 | {
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| 54 | if (count) {
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| 55 | ssize_t size = full_read(fd, buf, count);
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| 56 | if (size != count)
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| 57 | bb_error_msg_and_die("short read");
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| 58 | }
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| 59 | }
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| 60 |
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| 61 | // Die with an error message if we can't read one character.
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| 62 | unsigned char xread_char(int fd)
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| 63 | {
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| 64 | char tmp;
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| 65 | xread(fd, &tmp, 1);
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| 66 | return tmp;
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| 67 | }
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| 68 |
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| 69 | // Read one line a-la fgets. Works only on seekable streams
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| 70 | char *reads(int fd, char *buffer, size_t size)
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| 71 | {
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| 72 | char *p;
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| 73 |
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| 74 | if (size < 2)
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| 75 | return NULL;
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| 76 | size = full_read(fd, buffer, size-1);
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| 77 | if ((ssize_t)size <= 0)
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| 78 | return NULL;
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| 79 |
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| 80 | buffer[size] = '\0';
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| 81 | p = strchr(buffer, '\n');
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| 82 | if (p) {
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| 83 | off_t offset;
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| 84 | *p++ = '\0';
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| 85 | // avoid incorrect (unsigned) widening
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| 86 | offset = (off_t)(p-buffer) - (off_t)size;
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| 87 | // set fd position right after '\n'
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| 88 | if (offset && lseek(fd, offset, SEEK_CUR) == (off_t)-1)
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| 89 | return NULL;
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| 90 | }
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| 91 | return buffer;
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| 92 | }
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| 93 |
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| 94 | // Read one line a-la fgets. Reads byte-by-byte.
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| 95 | // Useful when it is important to not read ahead.
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| 96 | char *xmalloc_reads(int fd, char *buf)
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| 97 | {
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| 98 | char *p;
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| 99 | int sz = buf ? strlen(buf) : 0;
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| 100 |
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| 101 | goto jump_in;
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| 102 | while (1) {
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| 103 | if (p - buf == sz) {
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| 104 | jump_in:
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| 105 | buf = xrealloc(buf, sz + 128);
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| 106 | p = buf + sz;
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| 107 | sz += 128;
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| 108 | }
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| 109 | if (safe_read(fd, p, 1) != 1) { /* EOF/error */
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| 110 | if (p == buf) {
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| 111 | /* we read nothing [and buf was NULL initially] */
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| 112 | free(buf);
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| 113 | return NULL;
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| 114 | }
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| 115 | break;
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| 116 | }
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| 117 | if (*p == '\n')
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| 118 | break;
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| 119 | p++;
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| 120 | }
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| 121 | *p++ = '\0';
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| 122 | return xrealloc(buf, p - buf);
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| 123 | }
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| 124 |
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| 125 | ssize_t read_close(int fd, void *buf, size_t size)
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| 126 | {
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| 127 | /*int e;*/
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| 128 | size = full_read(fd, buf, size);
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| 129 | /*e = errno;*/
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| 130 | close(fd);
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| 131 | /*errno = e;*/
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| 132 | return size;
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| 133 | }
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| 134 |
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| 135 | ssize_t open_read_close(const char *filename, void *buf, size_t size)
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| 136 | {
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| 137 | int fd = open(filename, O_RDONLY);
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| 138 | if (fd < 0)
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| 139 | return fd;
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| 140 | return read_close(fd, buf, size);
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| 141 | }
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| 142 |
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| 143 | // Read (potentially big) files in one go. File size is estimated by
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| 144 | // lseek to end.
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| 145 | void *xmalloc_open_read_close(const char *filename, size_t *sizep)
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| 146 | {
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| 147 | char *buf;
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| 148 | size_t size = sizep ? *sizep : INT_MAX;
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| 149 | int fd;
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| 150 | off_t len;
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| 151 |
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| 152 | fd = xopen(filename, O_RDONLY);
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| 153 | /* /proc/N/stat files report len 0 here */
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| 154 | /* In order to make such files readable, we add small const */
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| 155 | len = xlseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */
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| 156 | xlseek(fd, 0, SEEK_SET);
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| 157 | if (len < size)
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| 158 | size = len;
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| 159 | buf = xmalloc(size + 1);
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| 160 | size = read_close(fd, buf, size);
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| 161 | if ((ssize_t)size < 0)
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| 162 | bb_perror_msg_and_die("'%s'", filename);
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| 163 | xrealloc(buf, size + 1);
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| 164 | buf[size] = '\0';
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| 165 | if (sizep)
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| 166 | *sizep = size;
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| 167 | return buf;
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| 168 | }
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