1 /* vi: set sw=4 ts=4: */
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
11 #if ENABLE_FEATURE_MODPROBE_SMALL_ZIPPED
12 #include "unarchive.h"
15 ssize_t FAST_FUNC safe_read(int fd, void *buf, size_t count)
20 n = read(fd, buf, count);
21 } while (n < 0 && errno == EINTR);
26 /* Suppose that you are a shell. You start child processes.
27 * They work and eventually exit. You want to get user input.
28 * You read stdin. But what happens if last child switched
29 * its stdin into O_NONBLOCK mode?
31 * *** SURPRISE! It will affect the parent too! ***
32 * *** BIG SURPRISE! It stays even after child exits! ***
34 * This is a design bug in UNIX API.
35 * fcntl(0, F_SETFL, fcntl(0, F_GETFL, 0) | O_NONBLOCK);
36 * will set nonblocking mode not only on _your_ stdin, but
37 * also on stdin of your parent, etc.
41 * fcntl(fd2, F_SETFL, fcntl(fd2, F_GETFL, 0) | O_NONBLOCK);
42 * sets both fd1 and fd2 to O_NONBLOCK. This includes cases
43 * where duping is done implicitly by fork() etc.
46 * fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD, 0) | O_NONBLOCK);
47 * (note SETFD, not SETFL!) but such thing doesn't exist.
49 * Alternatively, we need nonblocking_read(fd, ...) which doesn't
50 * require O_NONBLOCK dance at all. Actually, it exists:
51 * n = recv(fd, buf, len, MSG_DONTWAIT);
53 * Enables non-blocking operation; if the operation
54 * would block, EAGAIN is returned."
55 * but recv() works only for sockets!
57 * So far I don't see any good solution, I can only propose
58 * that affected readers should be careful and use this routine,
59 * which detects EAGAIN and uses poll() to wait on the fd.
60 * Thankfully, poll() doesn't care about O_NONBLOCK flag.
62 ssize_t FAST_FUNC nonblock_safe_read(int fd, void *buf, size_t count)
68 n = safe_read(fd, buf, count);
69 if (n >= 0 || errno != EAGAIN)
71 /* fd is in O_NONBLOCK mode. Wait using poll and repeat */
73 pfd[0].events = POLLIN;
74 safe_poll(pfd, 1, -1);
79 * Read all of the supplied buffer from a file.
80 * This does multiple reads as necessary.
81 * Returns the amount read, or -1 on an error.
82 * A short read is returned on an end of file.
84 ssize_t FAST_FUNC full_read(int fd, void *buf, size_t len)
92 cc = safe_read(fd, buf, len);
96 /* we already have some! */
97 /* user can do another read to know the error code */
100 return cc; /* read() returns -1 on failure. */
104 buf = ((char *)buf) + cc;
112 /* Die with an error message if we can't read the entire buffer. */
113 void FAST_FUNC xread(int fd, void *buf, size_t count)
116 ssize_t size = full_read(fd, buf, count);
117 if ((size_t)size != count)
118 bb_error_msg_and_die("short read");
122 /* Die with an error message if we can't read one character. */
123 unsigned char FAST_FUNC xread_char(int fd)
130 // Reads one line a-la fgets (but doesn't save terminating '\n').
131 // Reads byte-by-byte. Useful when it is important to not read ahead.
132 // Bytes are appended to pfx (which must be malloced, or NULL).
133 char* FAST_FUNC xmalloc_reads(int fd, char *buf, size_t *maxsz_p)
136 size_t sz = buf ? strlen(buf) : 0;
137 size_t maxsz = maxsz_p ? *maxsz_p : MAXINT(size_t);
141 if ((size_t)(p - buf) == sz) {
143 buf = xrealloc(buf, sz + 128);
147 /* nonblock_safe_read() because we are used by e.g. shells */
148 if (nonblock_safe_read(fd, p, 1) != 1) { /* EOF/error */
149 if (p == buf) { /* we read nothing */
163 return xrealloc(buf, p - buf);
166 ssize_t FAST_FUNC read_close(int fd, void *buf, size_t size)
169 size = full_read(fd, buf, size);
176 ssize_t FAST_FUNC open_read_close(const char *filename, void *buf, size_t size)
178 int fd = open(filename, O_RDONLY);
181 return read_close(fd, buf, size);
185 // Read (potentially big) files in one go. File size is estimated
186 // by stat. Extra '\0' byte is appended.
187 void* FAST_FUNC xmalloc_read(int fd, size_t *maxsz_p)
190 size_t size, rd_size, total;
194 to_read = maxsz_p ? *maxsz_p : MAXINT(ssize_t); /* max to read */
196 /* Estimate file size */
197 st.st_size = 0; /* in case fstat fails, assume 0 */
199 /* /proc/N/stat files report st_size 0 */
200 /* In order to make such files readable, we add small const */
201 size = (st.st_size | 0x3ff) + 1;
208 buf = xrealloc(buf, total + size + 1);
209 rd_size = full_read(fd, buf + total, size);
210 if ((ssize_t)rd_size == (ssize_t)(-1)) { /* error */
215 if (rd_size < size) /* EOF */
217 if (to_read <= rd_size)
220 /* grow by 1/8, but in [1k..64k] bounds */
221 size = ((total / 8) | 0x3ff) + 1;
225 xrealloc(buf, total + 1);
233 #ifdef USING_LSEEK_TO_GET_SIZE
234 /* Alternatively, file size can be obtained by lseek to the end.
235 * The code is slightly bigger. Retained in case fstat approach
236 * will not work for some weird cases (/proc, block devices, etc).
237 * (NB: lseek also can fail to work for some weird files) */
239 // Read (potentially big) files in one go. File size is estimated by
241 void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
248 fd = open(filename, O_RDONLY);
252 /* /proc/N/stat files report len 0 here */
253 /* In order to make such files readable, we add small const */
254 size = 0x3ff; /* read only 1k on unseekable files */
255 len = lseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */
256 if (len != (off_t)-1) {
257 xlseek(fd, 0, SEEK_SET);
258 size = maxsz_p ? *maxsz_p : INT_MAX;
263 buf = xmalloc(size + 1);
264 size = read_close(fd, buf, size);
265 if ((ssize_t)size < 0) {
269 xrealloc(buf, size + 1);
278 // Read (potentially big) files in one go. File size is estimated
280 void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
285 fd = open(filename, O_RDONLY);
289 buf = xmalloc_read(fd, maxsz_p);
294 void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p)
296 void *buf = xmalloc_open_read_close(filename, maxsz_p);
298 bb_perror_msg_and_die("can't read '%s'", filename);
302 #if ENABLE_FEATURE_MODPROBE_SMALL_ZIPPED
303 void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
308 int fd = open(fname, O_RDONLY);
312 suffix = strrchr(fname, '.');
314 if (strcmp(suffix, ".gz") == 0)
315 open_transformer(fd, unpack_gz_stream, "gunzip");
316 else if (strcmp(suffix, ".bz2") == 0)
317 open_transformer(fd, unpack_bz2_stream, "bunzip2");
320 image = xmalloc_read(fd, maxsz_p);
322 bb_perror_msg("read error from '%s'", fname);