Contents of /tags/mkinitrd-6_2_2/busybox/libbb/get_line_from_file.c
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Sun May 30 12:33:03 2010 UTC (14 years, 4 months ago) by niro
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Sun May 30 12:33:03 2010 UTC (14 years, 4 months ago) by niro
File MIME type: text/plain
File size: 4941 byte(s)
tagged 'mkinitrd-6_2_2'
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 tarball for details. |
10 | */ |
11 | |
12 | /* for getline() [GNUism] |
13 | #ifndef _GNU_SOURCE |
14 | #define _GNU_SOURCE 1 |
15 | #endif |
16 | */ |
17 | #include "libbb.h" |
18 | |
19 | /* This function reads an entire line from a text file, up to a newline |
20 | * or NUL byte, inclusive. It returns a malloc'ed char * which |
21 | * must be free'ed by the caller. If end is NULL '\n' isn't considered |
22 | * end of line. If end isn't NULL, length of the chunk is stored in it. |
23 | * If lineno is not NULL, *lineno is incremented for each line, |
24 | * and also trailing '\' is recognized as line continuation. |
25 | * |
26 | * Returns NULL if EOF/error. */ |
27 | char* FAST_FUNC bb_get_chunk_with_continuation(FILE *file, int *end, int *lineno) |
28 | { |
29 | int ch; |
30 | int idx = 0; |
31 | char *linebuf = NULL; |
32 | int linebufsz = 0; |
33 | |
34 | while ((ch = getc(file)) != EOF) { |
35 | /* grow the line buffer as necessary */ |
36 | if (idx >= linebufsz) { |
37 | linebufsz += 256; |
38 | linebuf = xrealloc(linebuf, linebufsz); |
39 | } |
40 | linebuf[idx++] = (char) ch; |
41 | if (!ch) |
42 | break; |
43 | if (end && ch == '\n') { |
44 | if (lineno == NULL) |
45 | break; |
46 | (*lineno)++; |
47 | if (idx < 2 || linebuf[idx-2] != '\\') |
48 | break; |
49 | idx -= 2; |
50 | } |
51 | } |
52 | if (end) |
53 | *end = idx; |
54 | if (linebuf) { |
55 | // huh, does fgets discard prior data on error like this? |
56 | // I don't think so.... |
57 | //if (ferror(file)) { |
58 | // free(linebuf); |
59 | // return NULL; |
60 | //} |
61 | linebuf = xrealloc(linebuf, idx + 1); |
62 | linebuf[idx] = '\0'; |
63 | } |
64 | return linebuf; |
65 | } |
66 | |
67 | char* FAST_FUNC bb_get_chunk_from_file(FILE *file, int *end) |
68 | { |
69 | return bb_get_chunk_with_continuation(file, end, NULL); |
70 | } |
71 | |
72 | /* Get line, including trailing \n if any */ |
73 | char* FAST_FUNC xmalloc_fgets(FILE *file) |
74 | { |
75 | int i; |
76 | |
77 | return bb_get_chunk_from_file(file, &i); |
78 | } |
79 | /* Get line. Remove trailing \n */ |
80 | char* FAST_FUNC xmalloc_fgetline(FILE *file) |
81 | { |
82 | int i; |
83 | char *c = bb_get_chunk_from_file(file, &i); |
84 | |
85 | if (i && c[--i] == '\n') |
86 | c[i] = '\0'; |
87 | |
88 | return c; |
89 | } |
90 | |
91 | #if 0 |
92 | /* GNUism getline() should be faster (not tested) than a loop with fgetc */ |
93 | |
94 | /* Get line, including trailing \n if any */ |
95 | char* FAST_FUNC xmalloc_fgets(FILE *file) |
96 | { |
97 | char *res_buf = NULL; |
98 | size_t res_sz; |
99 | |
100 | if (getline(&res_buf, &res_sz, file) == -1) { |
101 | free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */ |
102 | res_buf = NULL; |
103 | } |
104 | //TODO: trimming to res_sz? |
105 | return res_buf; |
106 | } |
107 | /* Get line. Remove trailing \n */ |
108 | char* FAST_FUNC xmalloc_fgetline(FILE *file) |
109 | { |
110 | char *res_buf = NULL; |
111 | size_t res_sz; |
112 | |
113 | res_sz = getline(&res_buf, &res_sz, file); |
114 | |
115 | if ((ssize_t)res_sz != -1) { |
116 | if (res_buf[res_sz - 1] == '\n') |
117 | res_buf[--res_sz] = '\0'; |
118 | //TODO: trimming to res_sz? |
119 | } else { |
120 | free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */ |
121 | res_buf = NULL; |
122 | } |
123 | return res_buf; |
124 | } |
125 | |
126 | #endif |
127 | |
128 | #if 0 |
129 | /* Faster routines (~twice as fast). +170 bytes. Unused as of 2008-07. |
130 | * |
131 | * NB: they stop at NUL byte too. |
132 | * Performance is important here. Think "grep 50gigabyte_file"... |
133 | * Ironically, grep can't use it because of NUL issue. |
134 | * We sorely need C lib to provide fgets which reports size! |
135 | * |
136 | * Update: |
137 | * Actually, uclibc and glibc have it. man getline. It's GNUism, |
138 | * but very useful one (if it's as fast as this code). |
139 | * TODO: |
140 | * - currently, sed and sort use bb_get_chunk_from_file and heavily |
141 | * depend on its "stop on \n or \0" behavior, and STILL they fail |
142 | * to handle all cases with embedded NULs correctly. So: |
143 | * - audit sed and sort; convert them to getline FIRST. |
144 | * - THEN ditch bb_get_chunk_from_file, replace it with getline. |
145 | * - provide getline implementation for non-GNU systems. |
146 | */ |
147 | |
148 | static char* xmalloc_fgets_internal(FILE *file, int *sizep) |
149 | { |
150 | int len; |
151 | int idx = 0; |
152 | char *linebuf = NULL; |
153 | |
154 | while (1) { |
155 | char *r; |
156 | |
157 | linebuf = xrealloc(linebuf, idx + 0x100); |
158 | r = fgets(&linebuf[idx], 0x100, file); |
159 | if (!r) { |
160 | /* need to terminate in case this is error |
161 | * (EOF puts NUL itself) */ |
162 | linebuf[idx] = '\0'; |
163 | break; |
164 | } |
165 | /* stupid. fgets knows the len, it should report it somehow */ |
166 | len = strlen(&linebuf[idx]); |
167 | idx += len; |
168 | if (len != 0xff || linebuf[idx - 1] == '\n') |
169 | break; |
170 | } |
171 | *sizep = idx; |
172 | if (idx) { |
173 | /* xrealloc(linebuf, idx + 1) is up to caller */ |
174 | return linebuf; |
175 | } |
176 | free(linebuf); |
177 | return NULL; |
178 | } |
179 | |
180 | /* Get line, remove trailing \n */ |
181 | char* FAST_FUNC xmalloc_fgetline_fast(FILE *file) |
182 | { |
183 | int sz; |
184 | char *r = xmalloc_fgets_internal(file, &sz); |
185 | if (r && r[sz - 1] == '\n') |
186 | r[--sz] = '\0'; |
187 | return r; /* not xrealloc(r, sz + 1)! */ |
188 | } |
189 | |
190 | char* FAST_FUNC xmalloc_fgets(FILE *file) |
191 | { |
192 | int sz; |
193 | return xmalloc_fgets_internal(file, &sz); |
194 | } |
195 | |
196 | /* Get line, remove trailing \n */ |
197 | char* FAST_FUNC xmalloc_fgetline(FILE *file) |
198 | { |
199 | int sz; |
200 | char *r = xmalloc_fgets_internal(file, &sz); |
201 | if (!r) |
202 | return r; |
203 | if (r[sz - 1] == '\n') |
204 | r[--sz] = '\0'; |
205 | return xrealloc(r, sz + 1); |
206 | } |
207 | #endif |