diff options
Diffstat (limited to 'libbb/read_printf.c')
-rw-r--r-- | libbb/read_printf.c | 374 |
1 files changed, 374 insertions, 0 deletions
diff --git a/libbb/read_printf.c b/libbb/read_printf.c new file mode 100644 index 000000000..53f528f5a --- /dev/null +++ b/libbb/read_printf.c | |||
@@ -0,0 +1,374 @@ | |||
1 | /* vi: set sw=4 ts=4: */ | ||
2 | /* | ||
3 | * Utility routines. | ||
4 | * | ||
5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> | ||
6 | * | ||
7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. | ||
8 | */ | ||
9 | #include "libbb.h" | ||
10 | |||
11 | #define ZIPPED (ENABLE_FEATURE_SEAMLESS_LZMA \ | ||
12 | || ENABLE_FEATURE_SEAMLESS_BZ2 \ | ||
13 | || ENABLE_FEATURE_SEAMLESS_GZ \ | ||
14 | /* || ENABLE_FEATURE_SEAMLESS_Z */ \ | ||
15 | ) | ||
16 | |||
17 | #if ZIPPED | ||
18 | # include "unarchive.h" | ||
19 | #endif | ||
20 | |||
21 | |||
22 | /* Suppose that you are a shell. You start child processes. | ||
23 | * They work and eventually exit. You want to get user input. | ||
24 | * You read stdin. But what happens if last child switched | ||
25 | * its stdin into O_NONBLOCK mode? | ||
26 | * | ||
27 | * *** SURPRISE! It will affect the parent too! *** | ||
28 | * *** BIG SURPRISE! It stays even after child exits! *** | ||
29 | * | ||
30 | * This is a design bug in UNIX API. | ||
31 | * fcntl(0, F_SETFL, fcntl(0, F_GETFL) | O_NONBLOCK); | ||
32 | * will set nonblocking mode not only on _your_ stdin, but | ||
33 | * also on stdin of your parent, etc. | ||
34 | * | ||
35 | * In general, | ||
36 | * fd2 = dup(fd1); | ||
37 | * fcntl(fd2, F_SETFL, fcntl(fd2, F_GETFL) | O_NONBLOCK); | ||
38 | * sets both fd1 and fd2 to O_NONBLOCK. This includes cases | ||
39 | * where duping is done implicitly by fork() etc. | ||
40 | * | ||
41 | * We need | ||
42 | * fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD) | O_NONBLOCK); | ||
43 | * (note SETFD, not SETFL!) but such thing doesn't exist. | ||
44 | * | ||
45 | * Alternatively, we need nonblocking_read(fd, ...) which doesn't | ||
46 | * require O_NONBLOCK dance at all. Actually, it exists: | ||
47 | * n = recv(fd, buf, len, MSG_DONTWAIT); | ||
48 | * "MSG_DONTWAIT: | ||
49 | * Enables non-blocking operation; if the operation | ||
50 | * would block, EAGAIN is returned." | ||
51 | * but recv() works only for sockets! | ||
52 | * | ||
53 | * So far I don't see any good solution, I can only propose | ||
54 | * that affected readers should be careful and use this routine, | ||
55 | * which detects EAGAIN and uses poll() to wait on the fd. | ||
56 | * Thankfully, poll() doesn't care about O_NONBLOCK flag. | ||
57 | */ | ||
58 | ssize_t FAST_FUNC nonblock_safe_read(int fd, void *buf, size_t count) | ||
59 | { | ||
60 | struct pollfd pfd[1]; | ||
61 | ssize_t n; | ||
62 | |||
63 | while (1) { | ||
64 | n = safe_read(fd, buf, count); | ||
65 | if (n >= 0 || errno != EAGAIN) | ||
66 | return n; | ||
67 | /* fd is in O_NONBLOCK mode. Wait using poll and repeat */ | ||
68 | pfd[0].fd = fd; | ||
69 | pfd[0].events = POLLIN; | ||
70 | safe_poll(pfd, 1, -1); /* note: this pulls in printf */ | ||
71 | } | ||
72 | } | ||
73 | |||
74 | // Reads one line a-la fgets (but doesn't save terminating '\n'). | ||
75 | // Reads byte-by-byte. Useful when it is important to not read ahead. | ||
76 | // Bytes are appended to pfx (which must be malloced, or NULL). | ||
77 | char* FAST_FUNC xmalloc_reads(int fd, char *buf, size_t *maxsz_p) | ||
78 | { | ||
79 | char *p; | ||
80 | size_t sz = buf ? strlen(buf) : 0; | ||
81 | size_t maxsz = maxsz_p ? *maxsz_p : (INT_MAX - 4095); | ||
82 | |||
83 | goto jump_in; | ||
84 | while (sz < maxsz) { | ||
85 | if ((size_t)(p - buf) == sz) { | ||
86 | jump_in: | ||
87 | buf = xrealloc(buf, sz + 128); | ||
88 | p = buf + sz; | ||
89 | sz += 128; | ||
90 | } | ||
91 | /* nonblock_safe_read() because we are used by e.g. shells */ | ||
92 | if (nonblock_safe_read(fd, p, 1) != 1) { /* EOF/error */ | ||
93 | if (p == buf) { /* we read nothing */ | ||
94 | free(buf); | ||
95 | return NULL; | ||
96 | } | ||
97 | break; | ||
98 | } | ||
99 | if (*p == '\n') | ||
100 | break; | ||
101 | p++; | ||
102 | } | ||
103 | *p = '\0'; | ||
104 | if (maxsz_p) | ||
105 | *maxsz_p = p - buf; | ||
106 | p++; | ||
107 | return xrealloc(buf, p - buf); | ||
108 | } | ||
109 | |||
110 | // Read (potentially big) files in one go. File size is estimated | ||
111 | // by stat. Extra '\0' byte is appended. | ||
112 | void* FAST_FUNC xmalloc_read(int fd, size_t *maxsz_p) | ||
113 | { | ||
114 | char *buf; | ||
115 | size_t size, rd_size, total; | ||
116 | size_t to_read; | ||
117 | struct stat st; | ||
118 | |||
119 | to_read = maxsz_p ? *maxsz_p : (INT_MAX - 4095); /* max to read */ | ||
120 | |||
121 | /* Estimate file size */ | ||
122 | st.st_size = 0; /* in case fstat fails, assume 0 */ | ||
123 | fstat(fd, &st); | ||
124 | /* /proc/N/stat files report st_size 0 */ | ||
125 | /* In order to make such files readable, we add small const */ | ||
126 | size = (st.st_size | 0x3ff) + 1; | ||
127 | |||
128 | total = 0; | ||
129 | buf = NULL; | ||
130 | while (1) { | ||
131 | if (to_read < size) | ||
132 | size = to_read; | ||
133 | buf = xrealloc(buf, total + size + 1); | ||
134 | rd_size = full_read(fd, buf + total, size); | ||
135 | if ((ssize_t)rd_size == (ssize_t)(-1)) { /* error */ | ||
136 | free(buf); | ||
137 | return NULL; | ||
138 | } | ||
139 | total += rd_size; | ||
140 | if (rd_size < size) /* EOF */ | ||
141 | break; | ||
142 | if (to_read <= rd_size) | ||
143 | break; | ||
144 | to_read -= rd_size; | ||
145 | /* grow by 1/8, but in [1k..64k] bounds */ | ||
146 | size = ((total / 8) | 0x3ff) + 1; | ||
147 | if (size > 64*1024) | ||
148 | size = 64*1024; | ||
149 | } | ||
150 | buf = xrealloc(buf, total + 1); | ||
151 | buf[total] = '\0'; | ||
152 | |||
153 | if (maxsz_p) | ||
154 | *maxsz_p = total; | ||
155 | return buf; | ||
156 | } | ||
157 | |||
158 | #ifdef USING_LSEEK_TO_GET_SIZE | ||
159 | /* Alternatively, file size can be obtained by lseek to the end. | ||
160 | * The code is slightly bigger. Retained in case fstat approach | ||
161 | * will not work for some weird cases (/proc, block devices, etc). | ||
162 | * (NB: lseek also can fail to work for some weird files) */ | ||
163 | |||
164 | // Read (potentially big) files in one go. File size is estimated by | ||
165 | // lseek to end. | ||
166 | void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p) | ||
167 | { | ||
168 | char *buf; | ||
169 | size_t size; | ||
170 | int fd; | ||
171 | off_t len; | ||
172 | |||
173 | fd = open(filename, O_RDONLY); | ||
174 | if (fd < 0) | ||
175 | return NULL; | ||
176 | |||
177 | /* /proc/N/stat files report len 0 here */ | ||
178 | /* In order to make such files readable, we add small const */ | ||
179 | size = 0x3ff; /* read only 1k on unseekable files */ | ||
180 | len = lseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */ | ||
181 | if (len != (off_t)-1) { | ||
182 | xlseek(fd, 0, SEEK_SET); | ||
183 | size = maxsz_p ? *maxsz_p : (INT_MAX - 4095); | ||
184 | if (len < size) | ||
185 | size = len; | ||
186 | } | ||
187 | |||
188 | buf = xmalloc(size + 1); | ||
189 | size = read_close(fd, buf, size); | ||
190 | if ((ssize_t)size < 0) { | ||
191 | free(buf); | ||
192 | return NULL; | ||
193 | } | ||
194 | buf = xrealloc(buf, size + 1); | ||
195 | buf[size] = '\0'; | ||
196 | |||
197 | if (maxsz_p) | ||
198 | *maxsz_p = size; | ||
199 | return buf; | ||
200 | } | ||
201 | #endif | ||
202 | |||
203 | // Read (potentially big) files in one go. File size is estimated | ||
204 | // by stat. | ||
205 | void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p) | ||
206 | { | ||
207 | char *buf; | ||
208 | int fd; | ||
209 | |||
210 | fd = open(filename, O_RDONLY); | ||
211 | if (fd < 0) | ||
212 | return NULL; | ||
213 | |||
214 | buf = xmalloc_read(fd, maxsz_p); | ||
215 | close(fd); | ||
216 | return buf; | ||
217 | } | ||
218 | |||
219 | /* Die with an error message if we can't read the entire buffer. */ | ||
220 | void FAST_FUNC xread(int fd, void *buf, size_t count) | ||
221 | { | ||
222 | if (count) { | ||
223 | ssize_t size = full_read(fd, buf, count); | ||
224 | if ((size_t)size != count) | ||
225 | bb_error_msg_and_die("short read"); | ||
226 | } | ||
227 | } | ||
228 | |||
229 | /* Die with an error message if we can't read one character. */ | ||
230 | unsigned char FAST_FUNC xread_char(int fd) | ||
231 | { | ||
232 | char tmp; | ||
233 | xread(fd, &tmp, 1); | ||
234 | return tmp; | ||
235 | } | ||
236 | |||
237 | void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p) | ||
238 | { | ||
239 | void *buf = xmalloc_open_read_close(filename, maxsz_p); | ||
240 | if (!buf) | ||
241 | bb_perror_msg_and_die("can't read '%s'", filename); | ||
242 | return buf; | ||
243 | } | ||
244 | |||
245 | /* Used by e.g. rpm which gives us a fd without filename, | ||
246 | * thus we can't guess the format from filename's extension. | ||
247 | */ | ||
248 | #if ZIPPED | ||
249 | void FAST_FUNC setup_unzip_on_fd(int fd /*, int fail_if_not_detected*/) | ||
250 | { | ||
251 | const int fail_if_not_detected = 1; | ||
252 | union { | ||
253 | uint8_t b[4]; | ||
254 | uint16_t b16[2]; | ||
255 | uint32_t b32[1]; | ||
256 | } magic; | ||
257 | int offset = -2; | ||
258 | # if BB_MMU | ||
259 | IF_DESKTOP(long long) int FAST_FUNC (*xformer)(int src_fd, int dst_fd); | ||
260 | enum { xformer_prog = 0 }; | ||
261 | # else | ||
262 | enum { xformer = 0 }; | ||
263 | const char *xformer_prog; | ||
264 | # endif | ||
265 | |||
266 | /* .gz and .bz2 both have 2-byte signature, and their | ||
267 | * unpack_XXX_stream wants this header skipped. */ | ||
268 | xread(fd, magic.b16, sizeof(magic.b16)); | ||
269 | if (ENABLE_FEATURE_SEAMLESS_GZ | ||
270 | && magic.b16[0] == GZIP_MAGIC | ||
271 | ) { | ||
272 | # if BB_MMU | ||
273 | xformer = unpack_gz_stream; | ||
274 | # else | ||
275 | xformer_prog = "gunzip"; | ||
276 | # endif | ||
277 | goto found_magic; | ||
278 | } | ||
279 | if (ENABLE_FEATURE_SEAMLESS_BZ2 | ||
280 | && magic.b16[0] == BZIP2_MAGIC | ||
281 | ) { | ||
282 | # if BB_MMU | ||
283 | xformer = unpack_bz2_stream; | ||
284 | # else | ||
285 | xformer_prog = "bunzip2"; | ||
286 | # endif | ||
287 | goto found_magic; | ||
288 | } | ||
289 | if (ENABLE_FEATURE_SEAMLESS_XZ | ||
290 | && magic.b16[0] == XZ_MAGIC1 | ||
291 | ) { | ||
292 | /* .xz signature: 0xfd, '7', 'z', 'X', 'Z', 0x00 */ | ||
293 | /* More info at: http://tukaani.org/xz/xz-file-format.txt */ | ||
294 | offset = -6; | ||
295 | xread(fd, magic.b32, sizeof(magic.b32)); | ||
296 | if (magic.b32[0] == XZ_MAGIC2) { | ||
297 | # if BB_MMU | ||
298 | xformer = unpack_xz_stream; | ||
299 | /* unpack_xz_stream wants fd at position 0 */ | ||
300 | xlseek(fd, offset, SEEK_CUR); | ||
301 | # else | ||
302 | xformer_prog = "unxz"; | ||
303 | # endif | ||
304 | goto found_magic; | ||
305 | } | ||
306 | } | ||
307 | |||
308 | /* No known magic seen */ | ||
309 | if (fail_if_not_detected) | ||
310 | bb_error_msg_and_die("no gzip" | ||
311 | IF_FEATURE_SEAMLESS_BZ2("/bzip2") | ||
312 | IF_FEATURE_SEAMLESS_XZ("/xz") | ||
313 | " magic"); | ||
314 | xlseek(fd, offset, SEEK_CUR); | ||
315 | return; | ||
316 | |||
317 | found_magic: | ||
318 | # if !BB_MMU | ||
319 | /* NOMMU version of open_transformer execs | ||
320 | * an external unzipper that wants | ||
321 | * file position at the start of the file */ | ||
322 | xlseek(fd, offset, SEEK_CUR); | ||
323 | # endif | ||
324 | open_transformer(fd, xformer, xformer_prog); | ||
325 | } | ||
326 | #endif /* ZIPPED */ | ||
327 | |||
328 | int FAST_FUNC open_zipped(const char *fname) | ||
329 | { | ||
330 | #if !ZIPPED | ||
331 | return open(fname, O_RDONLY); | ||
332 | #else | ||
333 | char *sfx; | ||
334 | int fd; | ||
335 | |||
336 | fd = open(fname, O_RDONLY); | ||
337 | if (fd < 0) | ||
338 | return fd; | ||
339 | |||
340 | sfx = strrchr(fname, '.'); | ||
341 | if (sfx) { | ||
342 | sfx++; | ||
343 | if (ENABLE_FEATURE_SEAMLESS_LZMA && strcmp(sfx, "lzma") == 0) | ||
344 | /* .lzma has no header/signature, just trust it */ | ||
345 | open_transformer(fd, unpack_lzma_stream, "unlzma"); | ||
346 | else | ||
347 | if ((ENABLE_FEATURE_SEAMLESS_GZ && strcmp(sfx, "gz") == 0) | ||
348 | || (ENABLE_FEATURE_SEAMLESS_BZ2 && strcmp(sfx, "bz2") == 0) | ||
349 | || (ENABLE_FEATURE_SEAMLESS_XZ && strcmp(sfx, "xz") == 0) | ||
350 | ) { | ||
351 | setup_unzip_on_fd(fd /*, fail_if_not_detected: 1*/); | ||
352 | } | ||
353 | } | ||
354 | |||
355 | return fd; | ||
356 | #endif | ||
357 | } | ||
358 | |||
359 | void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p) | ||
360 | { | ||
361 | int fd; | ||
362 | char *image; | ||
363 | |||
364 | fd = open_zipped(fname); | ||
365 | if (fd < 0) | ||
366 | return NULL; | ||
367 | |||
368 | image = xmalloc_read(fd, maxsz_p); | ||
369 | if (!image) | ||
370 | bb_perror_msg("read error from '%s'", fname); | ||
371 | close(fd); | ||
372 | |||
373 | return image; | ||
374 | } | ||