release/src/router/busybox/libbb/get_line_from_file.c

   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
  14 char* 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 */
  46 char* 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 */
  53 char* 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 */
  68 char* 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 */
  81 char* 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
 121 static 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 */
 154 char* 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
 163 char* 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 */
 170 char* 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