From 44dfd831d24f9b627ab666cf0973b0dce98fabba Mon Sep 17 00:00:00 2001 From: Mark Adler Date: Sun, 4 Dec 2016 17:09:33 -0800 Subject: Add gzfread(), duplicating the interface of fread(). --- zlib.h | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'zlib.h') diff --git a/zlib.h b/zlib.h index b396709..ff4469d 100644 --- a/zlib.h +++ b/zlib.h @@ -1388,7 +1388,35 @@ ZEXTERN int ZEXPORT gzread OF((gzFile file, voidp buf, unsigned len)); case. gzread returns the number of uncompressed bytes actually read, less than - len for end of file, or -1 for error. + len for end of file, or -1 for error. If len is too large to fit in an int, + then nothing is read, -1 is returned, and the error state is set to + Z_STREAM_ERROR. +*/ + +ZEXTERN z_size_t ZEXPORT gzfread OF((voidp buf, z_size_t size, z_size_t nitems, + gzFile file)); +/* + Read up to nitems items of size size from file to buf, otherwise operating + as gzread() does. This duplicates the interface of stdio's fread(), with + size_t request and return types. If the library defines size_t, then + z_size_t is identical to size_t. If not, then z_size_t is an unsigned + integer type that can contain a pointer. + + gzfread() returns the number of full items read of size size, or zero if + the end of the file was reached and a full item could not be read, or if + there was an error. gzerror() must be consulted if zero is returned in + order to determine if there was an error. If the multiplication of size and + nitems overflows, i.e. the product does not fit in a z_size_t, then nothing + is read, zero is returned, and the error state is set to Z_STREAM_ERROR. + + In the event that the end of file is reached and only a partial item is + available at the end, i.e. the remaining uncompressed data length is not a + multiple of size, then the final partial item is nevetheless read into buf + and the end-of-file flag is set. The length of the partial item read is not + provided, but could be inferred from the result of gztell(). This behavior + is the same as the behavior of fread() implementations in common libraries, + but it prevents the direct use of gzfread() to read a concurrently written + file, reseting and retrying on end-of-file, when size is not 1. */ ZEXTERN int ZEXPORT gzwrite OF((gzFile file, -- cgit v1.2.3-55-g6feb