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Diffstat (limited to 'zlib/gzread.c')
| -rw-r--r-- | zlib/gzread.c | 653 |
1 files changed, 653 insertions, 0 deletions
diff --git a/zlib/gzread.c b/zlib/gzread.c new file mode 100644 index 0000000..548201a --- /dev/null +++ b/zlib/gzread.c @@ -0,0 +1,653 @@ +/* gzread.c -- zlib functions for reading gzip files + * Copyright (C) 2004, 2005, 2010 Mark Adler + * For conditions of distribution and use, see copyright notice in zlib.h + */ + +#include "gzguts.h" + +/* Local functions */ +local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *)); +local int gz_avail OF((gz_statep)); +local int gz_next4 OF((gz_statep, unsigned long *)); +local int gz_head OF((gz_statep)); +local int gz_decomp OF((gz_statep)); +local int gz_make OF((gz_statep)); +local int gz_skip OF((gz_statep, z_off64_t)); + +/* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from + state->fd, and update state->eof, state->err, and state->msg as appropriate. + This function needs to loop on read(), since read() is not guaranteed to + read the number of bytes requested, depending on the type of descriptor. */ +local int gz_load(state, buf, len, have) + gz_statep state; + unsigned char *buf; + unsigned len; + unsigned *have; +{ + int ret; + + *have = 0; + do { + ret = read(state->fd, buf + *have, len - *have); + if (ret <= 0) + break; + *have += ret; + } while (*have < len); + if (ret < 0) { + gz_error(state, Z_ERRNO, zstrerror()); + return -1; + } + if (ret == 0) + state->eof = 1; + return 0; +} + +/* Load up input buffer and set eof flag if last data loaded -- return -1 on + error, 0 otherwise. Note that the eof flag is set when the end of the input + file is reached, even though there may be unused data in the buffer. Once + that data has been used, no more attempts will be made to read the file. + gz_avail() assumes that strm->avail_in == 0. */ +local int gz_avail(state) + gz_statep state; +{ + z_streamp strm = &(state->strm); + + if (state->err != Z_OK) + return -1; + if (state->eof == 0) { + if (gz_load(state, state->in, state->size, + (unsigned *)&(strm->avail_in)) == -1) + return -1; + strm->next_in = state->in; + } + return 0; +} + +/* Get next byte from input, or -1 if end or error. */ +#define NEXT() ((strm->avail_in == 0 && gz_avail(state) == -1) ? -1 : \ + (strm->avail_in == 0 ? -1 : \ + (strm->avail_in--, *(strm->next_in)++))) + +/* Get a four-byte little-endian integer and return 0 on success and the value + in *ret. Otherwise -1 is returned and *ret is not modified. */ +local int gz_next4(state, ret) + gz_statep state; + unsigned long *ret; +{ + int ch; + unsigned long val; + z_streamp strm = &(state->strm); + + val = NEXT(); + val += (unsigned)NEXT() << 8; + val += (unsigned long)NEXT() << 16; + ch = NEXT(); + if (ch == -1) + return -1; + val += (unsigned long)ch << 24; + *ret = val; + return 0; +} + +/* Look for gzip header, set up for inflate or copy. state->have must be zero. + If this is the first time in, allocate required memory. state->how will be + left unchanged if there is no more input data available, will be set to COPY + if there is no gzip header and direct copying will be performed, or it will + be set to GZIP for decompression, and the gzip header will be skipped so + that the next available input data is the raw deflate stream. If direct + copying, then leftover input data from the input buffer will be copied to + the output buffer. In that case, all further file reads will be directly to + either the output buffer or a user buffer. If decompressing, the inflate + state and the check value will be initialized. gz_head() will return 0 on + success or -1 on failure. Failures may include read errors or gzip header + errors. */ +local int gz_head(state) + gz_statep state; +{ + z_streamp strm = &(state->strm); + int flags; + unsigned len; + + /* allocate read buffers and inflate memory */ + if (state->size == 0) { + /* allocate buffers */ + state->in = malloc(state->want); + state->out = malloc(state->want << 1); + if (state->in == NULL || state->out == NULL) { + if (state->out != NULL) + free(state->out); + if (state->in != NULL) + free(state->in); + gz_error(state, Z_MEM_ERROR, "out of memory"); + return -1; + } + state->size = state->want; + + /* allocate inflate memory */ + state->strm.zalloc = Z_NULL; + state->strm.zfree = Z_NULL; + state->strm.opaque = Z_NULL; + state->strm.avail_in = 0; + state->strm.next_in = Z_NULL; + if (inflateInit2(&(state->strm), -15) != Z_OK) { /* raw inflate */ + free(state->out); + free(state->in); + state->size = 0; + gz_error(state, Z_MEM_ERROR, "out of memory"); + return -1; + } + } + + /* get some data in the input buffer */ + if (strm->avail_in == 0) { + if (gz_avail(state) == -1) + return -1; + if (strm->avail_in == 0) + return 0; + } + + /* look for the gzip magic header bytes 31 and 139 */ + if (strm->next_in[0] == 31) { + strm->avail_in--; + strm->next_in++; + if (strm->avail_in == 0 && gz_avail(state) == -1) + return -1; + if (strm->avail_in && strm->next_in[0] == 139) { + /* we have a gzip header, woo hoo! */ + strm->avail_in--; + strm->next_in++; + + /* skip rest of header */ + if (NEXT() != 8) { /* compression method */ + gz_error(state, Z_DATA_ERROR, "unknown compression method"); + return -1; + } + flags = NEXT(); + if (flags & 0xe0) { /* reserved flag bits */ + gz_error(state, Z_DATA_ERROR, "unknown header flags set"); + return -1; + } + NEXT(); /* modification time */ + NEXT(); + NEXT(); + NEXT(); + NEXT(); /* extra flags */ + NEXT(); /* operating system */ + if (flags & 4) { /* extra field */ + len = (unsigned)NEXT(); + len += (unsigned)NEXT() << 8; + while (len--) + if (NEXT() < 0) + break; + } + if (flags & 8) /* file name */ + while (NEXT() > 0) + ; + if (flags & 16) /* comment */ + while (NEXT() > 0) + ; + if (flags & 2) { /* header crc */ + NEXT(); + NEXT(); + } + /* an unexpected end of file is not checked for here -- it will be + noticed on the first request for uncompressed data */ + + /* set up for decompression */ + inflateReset(strm); + strm->adler = crc32(0L, Z_NULL, 0); + state->how = GZIP; + state->direct = 0; + return 0; + } + else { + /* not a gzip file -- save first byte (31) and fall to raw i/o */ + state->out[0] = 31; + state->have = 1; + } + } + + /* doing raw i/o, save start of raw data for seeking, copy any leftover + input to output -- this assumes that the output buffer is larger than + the input buffer, which also assures space for gzungetc() */ + state->raw = state->pos; + state->next = state->out; + if (strm->avail_in) { + memcpy(state->next + state->have, strm->next_in, strm->avail_in); + state->have += strm->avail_in; + strm->avail_in = 0; + } + state->how = COPY; + state->direct = 1; + return 0; +} + +/* Decompress from input to the provided next_out and avail_out in the state. + If the end of the compressed data is reached, then verify the gzip trailer + check value and length (modulo 2^32). state->have and state->next are set + to point to the just decompressed data, and the crc is updated. If the + trailer is verified, state->how is reset to LOOK to look for the next gzip + stream or raw data, once state->have is depleted. Returns 0 on success, -1 + on failure. Failures may include invalid compressed data or a failed gzip + trailer verification. */ +local int gz_decomp(state) + gz_statep state; +{ + int ret; + unsigned had; + unsigned long crc, len; + z_streamp strm = &(state->strm); + + /* fill output buffer up to end of deflate stream */ + had = strm->avail_out; + do { + /* get more input for inflate() */ + if (strm->avail_in == 0 && gz_avail(state) == -1) + return -1; + if (strm->avail_in == 0) { + gz_error(state, Z_DATA_ERROR, "unexpected end of file"); + return -1; + } + + /* decompress and handle errors */ + ret = inflate(strm, Z_NO_FLUSH); + if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) { + gz_error(state, Z_STREAM_ERROR, + "internal error: inflate stream corrupt"); + return -1; + } + if (ret == Z_MEM_ERROR) { + gz_error(state, Z_MEM_ERROR, "out of memory"); + return -1; + } + if (ret == Z_DATA_ERROR) { /* deflate stream invalid */ + gz_error(state, Z_DATA_ERROR, + strm->msg == NULL ? "compressed data error" : strm->msg); + return -1; + } + } while (strm->avail_out && ret != Z_STREAM_END); + + /* update available output and crc check value */ + state->have = had - strm->avail_out; + state->next = strm->next_out - state->have; + strm->adler = crc32(strm->adler, state->next, state->have); + + /* check gzip trailer if at end of deflate stream */ + if (ret == Z_STREAM_END) { + if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) { + gz_error(state, Z_DATA_ERROR, "unexpected end of file"); + return -1; + } + if (crc != strm->adler) { + gz_error(state, Z_DATA_ERROR, "incorrect data check"); + return -1; + } + if (len != (strm->total_out & 0xffffffffL)) { + gz_error(state, Z_DATA_ERROR, "incorrect length check"); + return -1; + } + state->how = LOOK; /* ready for next stream, once have is 0 (leave + state->direct unchanged to remember how) */ + } + + /* good decompression */ + return 0; +} + +/* Make data and put in the output buffer. Assumes that state->have == 0. + Data is either copied from the input file or decompressed from the input + file depending on state->how. If state->how is LOOK, then a gzip header is + looked for (and skipped if found) to determine wither to copy or decompress. + Returns -1 on error, otherwise 0. gz_make() will leave state->have as COPY + or GZIP unless the end of the input file has been reached and all data has + been processed. */ +local int gz_make(state) + gz_statep state; +{ + z_streamp strm = &(state->strm); + + if (state->how == LOOK) { /* look for gzip header */ + if (gz_head(state) == -1) + return -1; + if (state->have) /* got some data from gz_head() */ + return 0; + } + if (state->how == COPY) { /* straight copy */ + if (gz_load(state, state->out, state->size << 1, &(state->have)) == -1) + return -1; + state->next = state->out; + } + else if (state->how == GZIP) { /* decompress */ + strm->avail_out = state->size << 1; + strm->next_out = state->out; + if (gz_decomp(state) == -1) + return -1; + } + return 0; +} + +/* Skip len uncompressed bytes of output. Return -1 on error, 0 on success. */ +local int gz_skip(state, len) + gz_statep state; + z_off64_t len; +{ + unsigned n; + + /* skip over len bytes or reach end-of-file, whichever comes first */ + while (len) + /* skip over whatever is in output buffer */ + if (state->have) { + n = GT_OFF(state->have) || (z_off64_t)state->have > len ? + (unsigned)len : state->have; + state->have -= n; + state->next += n; + state->pos += n; + len -= n; + } + + /* output buffer empty -- return if we're at the end of the input */ + else if (state->eof && state->strm.avail_in == 0) + break; + + /* need more data to skip -- load up output buffer */ + else { + /* get more output, looking for header if required */ + if (gz_make(state) == -1) + return -1; + } + return 0; +} + +/* -- see zlib.h -- */ +int ZEXPORT gzread(file, buf, len) + gzFile file; + voidp buf; + unsigned len; +{ + unsigned got, n; + gz_statep state; + z_streamp strm; + + /* get internal structure */ + if (file == NULL) + return -1; + state = (gz_statep)file; + strm = &(state->strm); + + /* check that we're reading and that there's no error */ + if (state->mode != GZ_READ || state->err != Z_OK) + return -1; + + /* since an int is returned, make sure len fits in one, otherwise return + with an error (this avoids the flaw in the interface) */ + if ((int)len < 0) { + gz_error(state, Z_BUF_ERROR, "requested length does not fit in int"); + return -1; + } + + /* if len is zero, avoid unnecessary operations */ + if (len == 0) + return 0; + + /* process a skip request */ + if (state->seek) { + state->seek = 0; + if (gz_skip(state, state->skip) == -1) + return -1; + } + + /* get len bytes to buf, or less than len if at the end */ + got = 0; + do { + /* first just try copying data from the output buffer */ + if (state->have) { + n = state->have > len ? len : state->have; + memcpy(buf, state->next, n); + state->next += n; + state->have -= n; + } + + /* output buffer empty -- return if we're at the end of the input */ + else if (state->eof && strm->avail_in == 0) + break; + + /* need output data -- for small len or new stream load up our output + buffer */ + else if (state->how == LOOK || len < (state->size << 1)) { + /* get more output, looking for header if required */ + if (gz_make(state) == -1) + return -1; + continue; /* no progress yet -- go back to memcpy() above */ + /* the copy above assures that we will leave with space in the + output buffer, allowing at least one gzungetc() to succeed */ + } + + /* large len -- read directly into user buffer */ + else if (state->how == COPY) { /* read directly */ + if (gz_load(state, buf, len, &n) == -1) + return -1; + } + + /* large len -- decompress directly into user buffer */ + else { /* state->how == GZIP */ + strm->avail_out = len; + strm->next_out = buf; + if (gz_decomp(state) == -1) + return -1; + n = state->have; + state->have = 0; + } + + /* update progress */ + len -= n; + buf = (char *)buf + n; + got += n; + state->pos += n; + } while (len); + + /* return number of bytes read into user buffer (will fit in int) */ + return (int)got; +} + +/* -- see zlib.h -- */ +int ZEXPORT gzgetc(file) + gzFile file; +{ + int ret; + unsigned char buf[1]; + gz_statep state; + + /* get internal structure */ + if (file == NULL) + return -1; + state = (gz_statep)file; + + /* check that we're reading and that there's no error */ + if (state->mode != GZ_READ || state->err != Z_OK) + return -1; + + /* try output buffer (no need to check for skip request) */ + if (state->have) { + state->have--; + state->pos++; + return *(state->next)++; + } + + /* nothing there -- try gzread() */ + ret = gzread(file, buf, 1); + return ret < 1 ? -1 : buf[0]; +} + +/* -- see zlib.h -- */ +int ZEXPORT gzungetc(c, file) + int c; + gzFile file; +{ + gz_statep state; + + /* get internal structure */ + if (file == NULL) + return -1; + state = (gz_statep)file; + + /* check that we're reading and that there's no error */ + if (state->mode != GZ_READ || state->err != Z_OK) + return -1; + + /* process a skip request */ + if (state->seek) { + state->seek = 0; + if (gz_skip(state, state->skip) == -1) + return -1; + } + + /* can't push EOF */ + if (c < 0) + return -1; + + /* if output buffer empty, put byte at end (allows more pushing) */ + if (state->have == 0) { + state->have = 1; + state->next = state->out + (state->size << 1) - 1; + state->next[0] = c; + state->pos--; + return c; + } + + /* if no room, give up (must have already done a gzungetc()) */ + if (state->have == (state->size << 1)) { + gz_error(state, Z_BUF_ERROR, "out of room to push characters"); + return -1; + } + + /* slide output data if needed and insert byte before existing data */ + if (state->next == state->out) { + unsigned char *src = state->out + state->have; + unsigned char *dest = state->out + (state->size << 1); + while (src > state->out) + *--dest = *--src; + state->next = dest; + } + state->have++; + state->next--; + state->next[0] = c; + state->pos--; + return c; +} + +/* -- see zlib.h -- */ +char * ZEXPORT gzgets(file, buf, len) + gzFile file; + char *buf; + int len; +{ + unsigned left, n; + char *str; + unsigned char *eol; + gz_statep state; + + /* check parameters and get internal structure */ + if (file == NULL || buf == NULL || len < 1) + return NULL; + state = (gz_statep)file; + + /* check that we're reading and that there's no error */ + if (state->mode != GZ_READ || state->err != Z_OK) + return NULL; + + /* process a skip request */ + if (state->seek) { + state->seek = 0; + if (gz_skip(state, state->skip) == -1) + return NULL; + } + + /* copy output bytes up to new line or len - 1, whichever comes first -- + append a terminating zero to the string (we don't check for a zero in + the contents, let the user worry about that) */ + str = buf; + left = (unsigned)len - 1; + if (left) do { + /* assure that something is in the output buffer */ + if (state->have == 0) { + if (gz_make(state) == -1) + return NULL; /* error */ + if (state->have == 0) { /* end of file */ + if (buf == str) /* got bupkus */ + return NULL; + break; /* got something -- return it */ + } + } + + /* look for end-of-line in current output buffer */ + n = state->have > left ? left : state->have; + eol = memchr(state->next, '\n', n); + if (eol != NULL) + n = (unsigned)(eol - state->next) + 1; + + /* copy through end-of-line, or remainder if not found */ + memcpy(buf, state->next, n); + state->have -= n; + state->next += n; + state->pos += n; + left -= n; + buf += n; + } while (left && eol == NULL); + + /* found end-of-line or out of space -- terminate string and return it */ + buf[0] = 0; + return str; +} + +/* -- see zlib.h -- */ +int ZEXPORT gzdirect(file) + gzFile file; +{ + gz_statep state; + + /* get internal structure */ + if (file == NULL) + return 0; + state = (gz_statep)file; + + /* check that we're reading */ + if (state->mode != GZ_READ) + return 0; + + /* if the state is not known, but we can find out, then do so (this is + mainly for right after a gzopen() or gzdopen()) */ + if (state->how == LOOK && state->have == 0) + (void)gz_head(state); + + /* return 1 if reading direct, 0 if decompressing a gzip stream */ + return state->direct; +} + +/* -- see zlib.h -- */ +int ZEXPORT gzclose_r(file) + gzFile file; +{ + int ret; + gz_statep state; + + /* get internal structure */ + if (file == NULL) + return Z_STREAM_ERROR; + state = (gz_statep)file; + + /* check that we're reading */ + if (state->mode != GZ_READ) + return Z_STREAM_ERROR; + + /* free memory and close file */ + if (state->size) { + inflateEnd(&(state->strm)); + free(state->out); + free(state->in); + } + gz_error(state, Z_OK, NULL); + free(state->path); + ret = close(state->fd); + free(state); + return ret ? Z_ERRNO : Z_OK; +} |