source: branches/3.2/mindi-busybox/libbb/get_line_from_file.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
File size: 4.0 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
4 *
5 * Copyright (C) 2005, 2006 Rob Landley <rob@landley.net>
6 * Copyright (C) 2004 Erik Andersen <andersen@codepoet.org>
7 * Copyright (C) 2001 Matt Krai
8 *
9 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
10 */
11
12#include "libbb.h"
13
14char* FAST_FUNC bb_get_chunk_from_file(FILE *file, int *end)
15{
16    int ch;
17    unsigned idx = 0;
18    char *linebuf = NULL;
19
20    while ((ch = getc(file)) != EOF) {
21        /* grow the line buffer as necessary */
22        if (!(idx & 0xff))
23            linebuf = xrealloc(linebuf, idx + 0x100);
24        linebuf[idx++] = (char) ch;
25        if (ch == '\0')
26            break;
27        if (end && ch == '\n')
28            break;
29    }
30    if (end)
31        *end = idx;
32    if (linebuf) {
33        // huh, does fgets discard prior data on error like this?
34        // I don't think so....
35        //if (ferror(file)) {
36        //  free(linebuf);
37        //  return NULL;
38        //}
39        linebuf = xrealloc(linebuf, idx + 1);
40        linebuf[idx] = '\0';
41    }
42    return linebuf;
43}
44
45/* Get line, including trailing \n if any */
46char* FAST_FUNC xmalloc_fgets(FILE *file)
47{
48    int i;
49
50    return bb_get_chunk_from_file(file, &i);
51}
52/* Get line.  Remove trailing \n */
53char* FAST_FUNC xmalloc_fgetline(FILE *file)
54{
55    int i;
56    char *c = bb_get_chunk_from_file(file, &i);
57
58    if (i && c[--i] == '\n')
59        c[i] = '\0';
60
61    return c;
62}
63
64#if 0
65/* GNUism getline() should be faster (not tested) than a loop with fgetc */
66
67/* Get line, including trailing \n if any */
68char* FAST_FUNC xmalloc_fgets(FILE *file)
69{
70    char *res_buf = NULL;
71    size_t res_sz;
72
73    if (getline(&res_buf, &res_sz, file) == -1) {
74        free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */
75        res_buf = NULL;
76    }
77//TODO: trimming to res_sz?
78    return res_buf;
79}
80/* Get line.  Remove trailing \n */
81char* FAST_FUNC xmalloc_fgetline(FILE *file)
82{
83    char *res_buf = NULL;
84    size_t res_sz;
85
86    res_sz = getline(&res_buf, &res_sz, file);
87
88    if ((ssize_t)res_sz != -1) {
89        if (res_buf[res_sz - 1] == '\n')
90            res_buf[--res_sz] = '\0';
91//TODO: trimming to res_sz?
92    } else {
93        free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */
94        res_buf = NULL;
95    }
96    return res_buf;
97}
98
99#endif
100
101#if 0
102/* Faster routines (~twice as fast). +170 bytes. Unused as of 2008-07.
103 *
104 * NB: they stop at NUL byte too.
105 * Performance is important here. Think "grep 50gigabyte_file"...
106 * Ironically, grep can't use it because of NUL issue.
107 * We sorely need C lib to provide fgets which reports size!
108 *
109 * Update:
110 * Actually, uclibc and glibc have it. man getline. It's GNUism,
111 *   but very useful one (if it's as fast as this code).
112 * TODO:
113 * - currently, sed and sort use bb_get_chunk_from_file and heavily
114 *   depend on its "stop on \n or \0" behavior, and STILL they fail
115 *   to handle all cases with embedded NULs correctly. So:
116 * - audit sed and sort; convert them to getline FIRST.
117 * - THEN ditch bb_get_chunk_from_file, replace it with getline.
118 * - provide getline implementation for non-GNU systems.
119 */
120
121static char* xmalloc_fgets_internal(FILE *file, int *sizep)
122{
123    int len;
124    int idx = 0;
125    char *linebuf = NULL;
126
127    while (1) {
128        char *r;
129
130        linebuf = xrealloc(linebuf, idx + 0x100);
131        r = fgets(&linebuf[idx], 0x100, file);
132        if (!r) {
133            /* need to terminate in case this is error
134             * (EOF puts NUL itself) */
135            linebuf[idx] = '\0';
136            break;
137        }
138        /* stupid. fgets knows the len, it should report it somehow */
139        len = strlen(&linebuf[idx]);
140        idx += len;
141        if (len != 0xff || linebuf[idx - 1] == '\n')
142            break;
143    }
144    *sizep = idx;
145    if (idx) {
146        /* xrealloc(linebuf, idx + 1) is up to caller */
147        return linebuf;
148    }
149    free(linebuf);
150    return NULL;
151}
152
153/* Get line, remove trailing \n */
154char* FAST_FUNC xmalloc_fgetline_fast(FILE *file)
155{
156    int sz;
157    char *r = xmalloc_fgets_internal(file, &sz);
158    if (r && r[sz - 1] == '\n')
159        r[--sz] = '\0';
160    return r; /* not xrealloc(r, sz + 1)! */
161}
162
163char* FAST_FUNC xmalloc_fgets(FILE *file)
164{
165    int sz;
166    return xmalloc_fgets_internal(file, &sz);
167}
168
169/* Get line, remove trailing \n */
170char* FAST_FUNC xmalloc_fgetline(FILE *file)
171{
172    int sz;
173    char *r = xmalloc_fgets_internal(file, &sz);
174    if (!r)
175        return r;
176    if (r[sz - 1] == '\n')
177        r[--sz] = '\0';
178    return xrealloc(r, sz + 1);
179}
180#endif
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