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string-buffer: New module.

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* lib/string-buffer.h: New file.
* lib/string-buffer.c: New file.
* modules/string-buffer: New file.
* doc/posix-functions/open_memstream.texi: Mention the new module.
This commit is contained in:
Bruno Haible
2021-02-21 21:39:07 +01:00
parent df2105c7a6
commit 75461c74dc
5 changed files with 419 additions and 0 deletions
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8
ChangeLog
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@@ -1,3 +1,11 @@
2021-02-21 Bruno Haible <bruno@clisp.org>
string-buffer: New module.
* lib/string-buffer.h: New file.
* lib/string-buffer.c: New file.
* modules/string-buffer: New file.
* doc/posix-functions/open_memstream.texi: Mention the new module.
2021-02-21 Bruno Haible <bruno@clisp.org> 2021-02-21 Bruno Haible <bruno@clisp.org>
scratch_buffer: Document the exported API. scratch_buffer: Document the exported API.

3
doc/posix-functions/open_memstream.texi
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@@ -16,3 +16,6 @@ Portability problems not fixed by Gnulib:
This function is missing on some platforms: This function is missing on some platforms:
Mac OS X 10.5, FreeBSD 6.0, NetBSD 7.1, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 11.3, Cygwin 1.5.x, mingw, MSVC 14, Android 5.1. Mac OS X 10.5, FreeBSD 6.0, NetBSD 7.1, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 11.3, Cygwin 1.5.x, mingw, MSVC 14, Android 5.1.
@end itemize @end itemize
An alternative to the @code{open_memstream} function is the Gnulib module
@code{string-buffer}.

297
lib/string-buffer.c Normal file
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/* A buffer that accumulates a string by piecewise concatenation.
Copyright (C) 2021 Free Software Foundation, Inc.
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 2, 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 <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2021. */
#include <config.h>
/* Specification. */
#include "string-buffer.h"
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void
sb_init (struct string_buffer *buffer)
{
buffer->data = buffer->space;
buffer->length = 0;
buffer->allocated = sizeof (buffer->space);
buffer->error = false;
}
/* Ensures that INCREMENT bytes are available beyond the current used length
of BUFFER.
Returns 0, or -1 in case of out-of-memory error. */
static int
sb_ensure_more_bytes (struct string_buffer *buffer, size_t increment)
{
size_t incremented_length = buffer->length + increment;
if (incremented_length < increment)
/* Overflow. */
return -1;
if (buffer->allocated < incremented_length)
{
size_t new_allocated = 2 * buffer->allocated;
if (new_allocated < buffer->allocated)
/* Overflow. */
return -1;
if (new_allocated < incremented_length)
new_allocated = incremented_length;
char *new_data;
if (buffer->data == buffer->space)
{
new_data = (char *) malloc (new_allocated);
if (new_data == NULL)
/* Out-of-memory. */
return -1;
memcpy (new_data, buffer->data, buffer->length);
}
else
{
new_data = (char *) realloc (buffer->data, new_allocated);
if (new_data == NULL)
/* Out-of-memory. */
return -1;
}
buffer->data = new_data;
buffer->allocated = new_allocated;
}
return 0;
}
int
sb_append (struct string_buffer *buffer, const char *str)
{
size_t len = strlen (str);
if (sb_ensure_more_bytes (buffer, len) < 0)
{
buffer->error = true;
return -1;
}
memcpy (buffer->data + buffer->length, str, len);
buffer->length += len;
return 0;
}
int
sb_appendvf (struct string_buffer *buffer, const char *formatstring,
va_list list)
{
va_list list_copy;
/* Make a bit of room, so that the probability that the first vsnprintf() call
succeeds is high. */
size_t room = buffer->allocated - buffer->length;
if (room < 64)
{
if (sb_ensure_more_bytes (buffer, 64) < 0)
{
buffer->error = true;
return -1;
}
room = buffer->allocated - buffer->length;
}
va_copy (list_copy, list);
/* First vsnprintf() call. */
int ret = vsnprintf (buffer->data + buffer->length, room, formatstring, list);
if (ret < 0)
{
/* Failed. */
buffer->error = true;
ret = -1;
}
else
{
if ((size_t) ret <= room)
{
/* The result has fit into room bytes. */
buffer->length += (size_t) ret;
ret = 0;
}
else
{
/* The result was truncated. Make more room, for a second vsnprintf()
call. */
if (sb_ensure_more_bytes (buffer, (size_t) ret) < 0)
{
buffer->error = true;
ret = -1;
}
else
{
/* Second vsnprintf() call. */
room = buffer->allocated - buffer->length;
ret = vsnprintf (buffer->data + buffer->length, room,
formatstring, list_copy);
if (ret < 0)
{
/* Failed. */
buffer->error = true;
ret = -1;
}
else
{
if ((size_t) ret <= room)
{
/* The result has fit into room bytes. */
buffer->length += (size_t) ret;
ret = 0;
}
else
/* The return values of the vsnprintf() calls are not
consistent. */
abort ();
}
}
}
}
va_end (list_copy);
return ret;
}
int
sb_appendf (struct string_buffer *buffer, const char *formatstring, ...)
{
va_list args;
/* Make a bit of room, so that the probability that the first vsnprintf() call
succeeds is high. */
size_t room = buffer->allocated - buffer->length;
if (room < 64)
{
if (sb_ensure_more_bytes (buffer, 64) < 0)
{
buffer->error = true;
return -1;
}
room = buffer->allocated - buffer->length;
}
va_start (args, formatstring);
/* First vsnprintf() call. */
int ret = vsnprintf (buffer->data + buffer->length, room, formatstring, args);
if (ret < 0)
{
/* Failed. */
buffer->error = true;
ret = -1;
}
else
{
if ((size_t) ret <= room)
{
/* The result has fit into room bytes. */
buffer->length += (size_t) ret;
ret = 0;
}
else
{
/* The result was truncated. Make more room, for a second vsnprintf()
call. */
if (sb_ensure_more_bytes (buffer, (size_t) ret) < 0)
{
buffer->error = true;
ret = -1;
}
else
{
/* Second vsnprintf() call. */
room = buffer->allocated - buffer->length;
va_end (args);
va_start (args, formatstring);
ret = vsnprintf (buffer->data + buffer->length, room,
formatstring, args);
if (ret < 0)
{
/* Failed. */
buffer->error = true;
ret = -1;
}
else
{
if ((size_t) ret <= room)
{
/* The result has fit into room bytes. */
buffer->length += (size_t) ret;
ret = 0;
}
else
/* The return values of the vsnprintf() calls are not
consistent. */
abort ();
}
}
}
}
va_end (args);
return ret;
}
void
sb_free (struct string_buffer *buffer)
{
if (buffer->data != buffer->space)
free (buffer->data);
}
/* Returns the contents of BUFFER, and frees all other memory held
by BUFFER. Returns NULL upon failure or if there was an error earlier. */
char *
sb_dupfree (struct string_buffer *buffer)
{
if (buffer->error)
goto fail;
if (sb_ensure_more_bytes (buffer, 1) < 0)
goto fail;
buffer->data[buffer->length] = '\0';
buffer->length++;
if (buffer->data == buffer->space)
{
char *copy = (char *) malloc (buffer->length);
if (copy == NULL)
goto fail;
memcpy (copy, buffer->data, buffer->length);
return copy;
}
else
{
/* Shrink the string before returning it. */
char *contents = buffer->data;
if (buffer->length < buffer->allocated)
{
contents = realloc (contents, buffer->length);
if (contents == NULL)
goto fail;
}
return contents;
}
fail:
sb_free (buffer);
return NULL;
}

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lib/string-buffer.h Normal file
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/* A buffer that accumulates a string by piecewise concatenation.
Copyright (C) 2021 Free Software Foundation, Inc.
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 2, 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 <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2021. */
#ifndef _STRING_BUFFER_H
#define _STRING_BUFFER_H
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include "attribute.h"
/* A string buffer type. */
struct string_buffer
{
char *data;
size_t length; /* used bytes, <= allocated */
size_t allocated; /* allocated bytes */
bool error; /* true if there was an error */
char space[1024]; /* stack allocated space */
};
#ifdef __cplusplus
extern "C" {
#endif
/* Initializes BUFFER to the empty string. */
extern void sb_init (struct string_buffer *buffer);
/* Appends the contents of STR to BUFFER.
Returns 0, or -1 in case of out-of-memory error. */
extern int sb_append (struct string_buffer *buffer, const char *str);
/* Appends the result of the printf-compatible FORMATSTRING with the argument
list LIST to BUFFER.
Returns 0, or -1 in case of error. */
extern int sb_appendvf (struct string_buffer *buffer,
const char *formatstring, va_list list)
#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
ATTRIBUTE_FORMAT ((__gnu_printf__, 2, 0))
#else
ATTRIBUTE_FORMAT ((__printf__, 2, 0))
#endif
;
/* Appends the result of the printf-compatible FORMATSTRING with the following
arguments to BUFFER.
Returns 0, or -1 in case of error. */
extern int sb_appendf (struct string_buffer *buffer,
const char *formatstring, ...)
#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
ATTRIBUTE_FORMAT ((__gnu_printf__, 2, 3))
#else
ATTRIBUTE_FORMAT ((__printf__, 2, 3))
#endif
;
/* Frees the memory held by BUFFER. */
extern void sb_free (struct string_buffer *buffer);
/* Returns the contents of BUFFER, and frees all other memory held
by BUFFER. Returns NULL upon failure or if there was an error earlier.
It is the responsibility of the caller to free() the result. */
extern char * sb_dupfree (struct string_buffer *buffer);
#ifdef __cplusplus
}
#endif
#endif /* _STRING_BUFFER_H */

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modules/string-buffer Normal file
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Description:
A buffer that accumulates a string by piecewise concatenation.
Files:
lib/string-buffer.h
lib/string-buffer.c
Depends-on:
stdbool
attribute
stdarg
vsnprintf-posix
configure.ac:
Makefile.am:
lib_SOURCES += string-buffer.c
Include:
"string-buffer.h"
License:
LGPLv2+
Maintainer:
all