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 */ 58ssize_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). 77char* 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. 112void* 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. 166void* 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. 205void* 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. */ 220void 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. */ 230unsigned char FAST_FUNC xread_char(int fd) 231{ 232 char tmp; 233 xread(fd, &tmp, 1); 234 return tmp; 235} 236 237void* 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 249void 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[0])); 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 offset = -6; 293 xread(fd, magic.b32, sizeof(magic.b32[0])); 294 if (magic.b32[0] == XZ_MAGIC2) { 295# if BB_MMU 296 xformer = unpack_xz_stream; 297 /* unpack_xz_stream wants fd at position 6, no need to seek */ 298 //xlseek(fd, offset, SEEK_CUR); 299# else 300 xformer_prog = "unxz"; 301# endif 302 goto found_magic; 303 } 304 } 305 306 /* No known magic seen */ 307 if (fail_if_not_detected) 308 bb_error_msg_and_die("no gzip" 309 IF_FEATURE_SEAMLESS_BZ2("/bzip2") 310 IF_FEATURE_SEAMLESS_XZ("/xz") 311 " magic"); 312 xlseek(fd, offset, SEEK_CUR); 313 return; 314 315 found_magic: 316# if !BB_MMU 317 /* NOMMU version of open_transformer execs 318 * an external unzipper that wants 319 * file position at the start of the file */ 320 xlseek(fd, offset, SEEK_CUR); 321# endif 322 open_transformer(fd, xformer, xformer_prog); 323} 324#endif /* ZIPPED */ 325 326int FAST_FUNC open_zipped(const char *fname) 327{ 328#if !ZIPPED 329 return open(fname, O_RDONLY); 330#else 331 char *sfx; 332 int fd; 333 334 fd = open(fname, O_RDONLY); 335 if (fd < 0) 336 return fd; 337 338 sfx = strrchr(fname, '.'); 339 if (sfx) { 340 sfx++; 341 if (ENABLE_FEATURE_SEAMLESS_LZMA && strcmp(sfx, "lzma") == 0) 342 /* .lzma has no header/signature, just trust it */ 343 open_transformer(fd, unpack_lzma_stream, "unlzma"); 344 else 345 if ((ENABLE_FEATURE_SEAMLESS_GZ && strcmp(sfx, "gz") == 0) 346 || (ENABLE_FEATURE_SEAMLESS_BZ2 && strcmp(sfx, "bz2") == 0) 347 || (ENABLE_FEATURE_SEAMLESS_XZ && strcmp(sfx, "xz") == 0) 348 ) { 349 setup_unzip_on_fd(fd /*, fail_if_not_detected: 1*/); 350 } 351 } 352 353 return fd; 354#endif 355} 356 357void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p) 358{ 359 int fd; 360 char *image; 361 362 fd = open_zipped(fname); 363 if (fd < 0) 364 return NULL; 365 366 image = xmalloc_read(fd, maxsz_p); 367 if (!image) 368 bb_perror_msg("read error from '%s'", fname); 369 close(fd); 370 371 return image; 372} 373