/* gzread.c -- zlib functions for reading gzip files * Copyright (C) 2004, 2005, 2010, 2011, 2012, 2013, 2016 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_look OF((gz_statep)); local int gz_decomp OF((gz_statep)); local int gz_fetch OF((gz_statep)); local int gz_skip OF((gz_statep, z_off64_t)); local z_size_t gz_read OF((gz_statep, voidp, z_size_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; unsigned get, max = ((unsigned)-1 >> 2) + 1; *have = 0; do { get = len - *have; if (get > max) get = max; ret = read(state->fd, buf + *have, get); if (ret <= 0) break; *have += (unsigned)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. If strm->avail_in != 0, then the current data is moved to the beginning of the input buffer, and then the remainder of the buffer is loaded with the available data from the input file. */ local int gz_avail(state) gz_statep state; { unsigned got; z_streamp strm = &(state->strm); if (state->err != Z_OK && state->err != Z_BUF_ERROR) return -1; if (state->eof == 0) { if (strm->avail_in) { /* copy what's there to the start */ unsigned char *p = state->in; unsigned const char *q = strm->next_in; unsigned n = strm->avail_in; do { *p++ = *q++; } while (--n); } if (gz_load(state, state->in + strm->avail_in, state->size - strm->avail_in, &got) == -1) return -1; strm->avail_in += got; strm->next_in = state->in; } return 0; } /* Look for gzip header, set up for inflate or copy. state->x.have must be 0. 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. 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 will be initialized. gz_look() will return 0 on success or -1 on failure. */ local int gz_look(state) gz_statep state; { z_streamp strm = &(state->strm); /* allocate read buffers and inflate memory */ if (state->size == 0) { /* allocate buffers */ state->in = (unsigned char *)malloc(state->want); state->out = (unsigned char *)malloc(state->want << 1); if (state->in == NULL || state->out == NULL) { free(state->out); 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 + 16) != Z_OK) { /* gunzip */ free(state->out); free(state->in); state->size = 0; gz_error(state, Z_MEM_ERROR, "out of memory"); return -1; } } /* get at least the magic bytes in the input buffer */ if (strm->avail_in < 2) { if (gz_avail(state) == -1) return -1; if (strm->avail_in == 0) return 0; } /* look for gzip magic bytes -- if there, do gzip decoding (note: there is a logical dilemma here when considering the case of a partially written gzip file, to wit, if a single 31 byte is written, then we cannot tell whether this is a single-byte file, or just a partially written gzip file -- for here we assume that if a gzip file is b
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