[Patch v7 2/6] util: add gz_readline

Tomi Ollila tomi.ollila at iki.fi
Sun Apr 6 03:21:29 PDT 2014


On Sat, Apr 05 2014, David Bremner <david at tethera.net> wrote:

> The idea is to provide a more or less drop in replacement for readline
> to read from zlib/gzip streams.  Take the opportunity to replace
> malloc with talloc.
> ---
>  util/Makefile.local |  3 +-
>  util/util.c         | 24 +++++++++++++++
>  util/util.h         | 29 ++++++++++++++++++
>  util/zlib-extra.c   | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  util/zlib-extra.h   | 25 ++++++++++++++++
>  5 files changed, 165 insertions(+), 1 deletion(-)
>  create mode 100644 util/util.c
>  create mode 100644 util/util.h
>  create mode 100644 util/zlib-extra.c
>  create mode 100644 util/zlib-extra.h
>
> diff --git a/util/Makefile.local b/util/Makefile.local
> index 29c0ce6..905f237 100644
> --- a/util/Makefile.local
> +++ b/util/Makefile.local
> @@ -4,7 +4,8 @@ dir := util
>  extra_cflags += -I$(srcdir)/$(dir)
>  
>  libutil_c_srcs := $(dir)/xutil.c $(dir)/error_util.c $(dir)/hex-escape.c \
> -		  $(dir)/string-util.c $(dir)/talloc-extra.c
> +		  $(dir)/string-util.c $(dir)/talloc-extra.c $(dir)/zlib-extra.c \
> +		$(dir)/util.c
>  
>  libutil_modules := $(libutil_c_srcs:.c=.o)
>  
> diff --git a/util/util.c b/util/util.c
> new file mode 100644
> index 0000000..3bd305d
> --- /dev/null
> +++ b/util/util.c
> @@ -0,0 +1,24 @@
> +#include "util.h"
> +#include "error_util.h"
> +#include <string.h>
> +#include <errno.h>
> +
> +const char *
> +util_error_string (util_status_t errnum)
> +{
> +    switch (errnum) {
> +    case UTIL_SUCCESS:
> +	return "none";

The series gets OK from me. This "none" could be amended to "success" to be
'consistent' with libc strerror(0) -- which returns 'Success'.


Tomi


> +    case UTIL_OUT_OF_MEMORY:
> +	return "out of memory";
> +    case UTIL_EOF:
> +	return "end of file";
> +    case UTIL_ERRNO:
> +	return strerror (errno);
> +    case UTIL_GZERROR:
> +	/* we lack context to be more informative here */
> +	return "zlib error";
> +    default:
> +	INTERNAL_ERROR("unexpected error status %d", errnum);
> +    }
> +}
> diff --git a/util/util.h b/util/util.h
> new file mode 100644
> index 0000000..d12fadb
> --- /dev/null
> +++ b/util/util.h
> @@ -0,0 +1,29 @@
> +#ifndef _UTIL_H
> +#define _UTIL_H
> +
> +typedef enum util_status {
> +    /**
> +     * No error occurred.
> +     */
> +    UTIL_SUCCESS = 0,
> +    /**
> +     * Out of memory.
> +     */
> +    UTIL_OUT_OF_MEMORY,
> +    /**
> +     * End of stream reached while attempting to read.
> +     */
> +    UTIL_EOF,
> +    /**
> +     * Low level error occured, consult errno.
> +     */
> +    UTIL_ERRNO,
> +    /**
> +     * Zlib error occured, call gzerror for details.
> +     */
> +    UTIL_GZERROR
> +} util_status_t;
> +
> +const char *
> +util_error_string (util_status_t status);
> +#endif
> diff --git a/util/zlib-extra.c b/util/zlib-extra.c
> new file mode 100644
> index 0000000..cb34845
> --- /dev/null
> +++ b/util/zlib-extra.c
> @@ -0,0 +1,85 @@
> +/* zlib-extra.c -  Extra or enhanced routines for compressed I/O.
> + *
> + * Copyright (c) 2014 David Bremner
> + *
> + * This program is free software: you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, either version 3 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see http://www.gnu.org/licenses/ .
> + *
> + * Author: David Bremner <david at tethera.net>
> + */
> +
> +#include "zlib-extra.h"
> +#include <talloc.h>
> +#include <stdio.h>
> +#include <string.h>
> +
> +/* mimic POSIX/glibc getline, but on a zlib gzFile stream, and using talloc */
> +util_status_t
> +gz_getline (void *talloc_ctx, char **bufptr, ssize_t *bytes_read, gzFile stream)
> +{
> +    char *buf = *bufptr;
> +    unsigned int len;
> +    size_t offset = 0;
> +
> +    if (buf) {
> +	len = talloc_array_length (buf);
> +    } else {
> +	/* same as getdelim from gnulib */
> +	len = 120;
> +	buf = talloc_array (talloc_ctx, char, len);
> +	if (buf == NULL)
> +	    return UTIL_OUT_OF_MEMORY;
> +    }
> +
> +    while (1) {
> +	if (! gzgets (stream, buf + offset, len - offset)) {
> +	    /* Null indicates EOF or error */
> +	    int zlib_status = 0;
> +	    (void) gzerror (stream, &zlib_status);
> +	    switch (zlib_status) {
> +	    case Z_OK:
> +		/* no data read before EOF */
> +		if (offset == 0)
> +		    return UTIL_EOF;
> +		else
> +		    goto SUCCESS;
> +	    case Z_ERRNO:
> +		return UTIL_ERRNO;
> +	    default:
> +		return UTIL_GZERROR;
> +	    }
> +	}
> +
> +	offset += strlen (buf + offset);
> +
> +	if (buf[offset - 1] == '\n')
> +	    goto SUCCESS;
> +
> +	len *= 2;
> +	buf = talloc_realloc (talloc_ctx, buf, char, len);
> +	if (buf == NULL)
> +	    return UTIL_OUT_OF_MEMORY;
> +    }
> + SUCCESS:
> +    *bufptr = buf;
> +    *bytes_read = offset;
> +    return UTIL_SUCCESS;
> +}
> +
> +const char *gz_error_string (util_status_t status, gzFile file) 
> +{
> +    if (status == UTIL_GZERROR)
> +	return gzerror (file, NULL);
> +    else
> +	return util_error_string (status);
> +}
> diff --git a/util/zlib-extra.h b/util/zlib-extra.h
> new file mode 100644
> index 0000000..dbaa0b9
> --- /dev/null
> +++ b/util/zlib-extra.h
> @@ -0,0 +1,25 @@
> +#ifndef _ZLIB_EXTRA_H
> +#define _ZLIB_EXTRA_H
> +
> +#include "util.h"
> +#include <zlib.h>
> +
> +/* Like getline, but read from a gzFile. Allocation is with talloc.
> + * Returns:
> + *
> + *   UTIL_SUCCESS, UTIL_OUT_OF_MEMORY, UTIL_ERRNO, UTIL_GZERROR
> + *			Consult util.h for description
> + *
> + *   UTIL_EOF		End of file encountered before 
> + *			any characters read
> + */
> +util_status_t
> +gz_getline (void *ctx, char **lineptr, ssize_t *bytes_read, gzFile stream);
> +
> +/* return a suitable error string based on the return status
> + *  from gz_readline
> + */
> +
> +const char *
> +gz_error_string (util_status_t status, gzFile stream);
> +#endif
> -- 
> 1.9.0
>
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