Contents of /tags/mkinitrd-6_3_3/busybox/libbb/get_line_from_file.c
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Wed Dec 15 21:43:57 2010 UTC (13 years, 9 months ago) by niro
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Wed Dec 15 21:43:57 2010 UTC (13 years, 9 months ago) by niro
File MIME type: text/plain
File size: 4863 byte(s)
tagged 'mkinitrd-6_3_3'
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 | #include "libbb.h" |
13 | |
14 | /* This function reads an entire line from a text file, up to a newline |
15 | * or NUL byte, inclusive. It returns a malloc'ed char * which |
16 | * must be free'ed by the caller. If end is NULL '\n' isn't considered |
17 | * end of line. If end isn't NULL, length of the chunk is stored in it. |
18 | * If lineno is not NULL, *lineno is incremented for each line, |
19 | * and also trailing '\' is recognized as line continuation. |
20 | * |
21 | * Returns NULL if EOF/error. */ |
22 | char* FAST_FUNC bb_get_chunk_with_continuation(FILE *file, int *end, int *lineno) |
23 | { |
24 | int ch; |
25 | int idx = 0; |
26 | char *linebuf = NULL; |
27 | int linebufsz = 0; |
28 | |
29 | while ((ch = getc(file)) != EOF) { |
30 | /* grow the line buffer as necessary */ |
31 | if (idx >= linebufsz) { |
32 | linebufsz += 256; |
33 | linebuf = xrealloc(linebuf, linebufsz); |
34 | } |
35 | linebuf[idx++] = (char) ch; |
36 | if (!ch) |
37 | break; |
38 | if (end && ch == '\n') { |
39 | if (lineno == NULL) |
40 | break; |
41 | (*lineno)++; |
42 | if (idx < 2 || linebuf[idx-2] != '\\') |
43 | break; |
44 | idx -= 2; |
45 | } |
46 | } |
47 | if (end) |
48 | *end = idx; |
49 | if (linebuf) { |
50 | // huh, does fgets discard prior data on error like this? |
51 | // I don't think so.... |
52 | //if (ferror(file)) { |
53 | // free(linebuf); |
54 | // return NULL; |
55 | //} |
56 | linebuf = xrealloc(linebuf, idx + 1); |
57 | linebuf[idx] = '\0'; |
58 | } |
59 | return linebuf; |
60 | } |
61 | |
62 | char* FAST_FUNC bb_get_chunk_from_file(FILE *file, int *end) |
63 | { |
64 | return bb_get_chunk_with_continuation(file, end, NULL); |
65 | } |
66 | |
67 | /* Get line, including trailing \n if any */ |
68 | char* FAST_FUNC xmalloc_fgets(FILE *file) |
69 | { |
70 | int i; |
71 | |
72 | return bb_get_chunk_from_file(file, &i); |
73 | } |
74 | /* Get line. Remove trailing \n */ |
75 | char* FAST_FUNC xmalloc_fgetline(FILE *file) |
76 | { |
77 | int i; |
78 | char *c = bb_get_chunk_from_file(file, &i); |
79 | |
80 | if (i && c[--i] == '\n') |
81 | c[i] = '\0'; |
82 | |
83 | return c; |
84 | } |
85 | |
86 | #if 0 |
87 | /* GNUism getline() should be faster (not tested) than a loop with fgetc */ |
88 | |
89 | /* Get line, including trailing \n if any */ |
90 | char* FAST_FUNC xmalloc_fgets(FILE *file) |
91 | { |
92 | char *res_buf = NULL; |
93 | size_t res_sz; |
94 | |
95 | if (getline(&res_buf, &res_sz, file) == -1) { |
96 | free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */ |
97 | res_buf = NULL; |
98 | } |
99 | //TODO: trimming to res_sz? |
100 | return res_buf; |
101 | } |
102 | /* Get line. Remove trailing \n */ |
103 | char* FAST_FUNC xmalloc_fgetline(FILE *file) |
104 | { |
105 | char *res_buf = NULL; |
106 | size_t res_sz; |
107 | |
108 | res_sz = getline(&res_buf, &res_sz, file); |
109 | |
110 | if ((ssize_t)res_sz != -1) { |
111 | if (res_buf[res_sz - 1] == '\n') |
112 | res_buf[--res_sz] = '\0'; |
113 | //TODO: trimming to res_sz? |
114 | } else { |
115 | free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */ |
116 | res_buf = NULL; |
117 | } |
118 | return res_buf; |
119 | } |
120 | |
121 | #endif |
122 | |
123 | #if 0 |
124 | /* Faster routines (~twice as fast). +170 bytes. Unused as of 2008-07. |
125 | * |
126 | * NB: they stop at NUL byte too. |
127 | * Performance is important here. Think "grep 50gigabyte_file"... |
128 | * Ironically, grep can't use it because of NUL issue. |
129 | * We sorely need C lib to provide fgets which reports size! |
130 | * |
131 | * Update: |
132 | * Actually, uclibc and glibc have it. man getline. It's GNUism, |
133 | * but very useful one (if it's as fast as this code). |
134 | * TODO: |
135 | * - currently, sed and sort use bb_get_chunk_from_file and heavily |
136 | * depend on its "stop on \n or \0" behavior, and STILL they fail |
137 | * to handle all cases with embedded NULs correctly. So: |
138 | * - audit sed and sort; convert them to getline FIRST. |
139 | * - THEN ditch bb_get_chunk_from_file, replace it with getline. |
140 | * - provide getline implementation for non-GNU systems. |
141 | */ |
142 | |
143 | static char* xmalloc_fgets_internal(FILE *file, int *sizep) |
144 | { |
145 | int len; |
146 | int idx = 0; |
147 | char *linebuf = NULL; |
148 | |
149 | while (1) { |
150 | char *r; |
151 | |
152 | linebuf = xrealloc(linebuf, idx + 0x100); |
153 | r = fgets(&linebuf[idx], 0x100, file); |
154 | if (!r) { |
155 | /* need to terminate in case this is error |
156 | * (EOF puts NUL itself) */ |
157 | linebuf[idx] = '\0'; |
158 | break; |
159 | } |
160 | /* stupid. fgets knows the len, it should report it somehow */ |
161 | len = strlen(&linebuf[idx]); |
162 | idx += len; |
163 | if (len != 0xff || linebuf[idx - 1] == '\n') |
164 | break; |
165 | } |
166 | *sizep = idx; |
167 | if (idx) { |
168 | /* xrealloc(linebuf, idx + 1) is up to caller */ |
169 | return linebuf; |
170 | } |
171 | free(linebuf); |
172 | return NULL; |
173 | } |
174 | |
175 | /* Get line, remove trailing \n */ |
176 | char* FAST_FUNC xmalloc_fgetline_fast(FILE *file) |
177 | { |
178 | int sz; |
179 | char *r = xmalloc_fgets_internal(file, &sz); |
180 | if (r && r[sz - 1] == '\n') |
181 | r[--sz] = '\0'; |
182 | return r; /* not xrealloc(r, sz + 1)! */ |
183 | } |
184 | |
185 | char* FAST_FUNC xmalloc_fgets(FILE *file) |
186 | { |
187 | int sz; |
188 | return xmalloc_fgets_internal(file, &sz); |
189 | } |
190 | |
191 | /* Get line, remove trailing \n */ |
192 | char* FAST_FUNC xmalloc_fgetline(FILE *file) |
193 | { |
194 | int sz; |
195 | char *r = xmalloc_fgets_internal(file, &sz); |
196 | if (!r) |
197 | return r; |
198 | if (r[sz - 1] == '\n') |
199 | r[--sz] = '\0'; |
200 | return xrealloc(r, sz + 1); |
201 | } |
202 | #endif |