Re: strfile: new module

[Simon Josefsson]

Simon Josefsson <address@hidden> writes:

> I like this, and I also like your fread_file function.  I will create
> a module read-file with two functions fread_file and read_file.

Here's the module.  Only lighted tested, mostly to get feedback on the
approach, but if you agree with it, detailed review would be useful.

Index: lib/read-file.c
===================================================================
RCS file: lib/read-file.c
diff -N lib/read-file.c
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ lib/read-file.c     31 May 2006 13:25:27 -0000
@@ -0,0 +1,141 @@
+/* read-file.c -- read file contents into a string
+   Copyright (C) 2006 Free Software Foundation, Inc.
+   Written by Simon Josefsson and Bruno Haible.
+
+   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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "read-file.h"
+
+/* Get realloc, free. */
+#include <stdlib.h>
+
+/* Get errno. */
+#include <errno.h>
+
+/* Read a STREAM and return a newly allocated string with the content,
+   and set LENGTH to the length of the string.  The string is
+   zero-terminated, but the terminating zero character is not counted
+   in the LENGTH variable.  On errors, return NULL, sets errno and
+   LENGTH is undefined. */
+char *
+fread_file (FILE * stream, size_t * length)
+{
+  char *buf = NULL;
+  size_t alloc = 0;
+  size_t size = 0;
+
+  while (!feof (stream))
+    {
+      size_t count;
+
+      if (size + BUFSIZ + 1 > alloc)
+       {
+         char *tmp;
+
+         alloc += alloc / 2;
+         if (alloc < size + BUFSIZ + 1)
+           alloc = size + BUFSIZ + 1;
+
+         tmp = realloc (buf, alloc);
+         if (!tmp)
+           {
+             int save_errno = errno;
+             if (buf)
+               free (buf);
+             errno = save_errno;
+             return NULL;
+           }
+
+         buf = tmp;
+       }
+
+      count = fread (buf + size, 1, BUFSIZ, stream);
+      size += count;
+
+      if (ferror (stream))
+       {
+         int save_errno = errno;
+         free (buf);
+         errno = save_errno;
+         return NULL;
+       }
+    }
+
+  buf[size] = '\0';
+
+  *length = size;
+
+  return buf;
+}
+
+static char *
+internal_read_file (const char *filename, size_t * length, const char *mode)
+{
+  FILE *stream = fopen (filename, mode);
+  char *out = NULL;
+  int rc;
+
+  if (!stream)
+    return NULL;
+
+  out = fread_file (stream, length);
+
+  if (out)
+    rc = fclose (stream);
+  else
+    {
+      /* On failure, preserve the original errno value. */
+      int save_errno = errno;
+      rc = fclose (stream);
+      errno = save_errno;
+    }
+
+  if (rc != 0)
+    {
+      int save_errno = errno;
+      if (out)
+       free (out);
+      errno = save_errno;
+      return NULL;
+    }
+
+  return out;
+}
+
+/* Open and read the contents of FILENAME, and return a newly
+   allocated string with the content, and set LENGTH to the length of
+   the string.  The string is zero-terminated, but the terminating
+   zero character is not counted in the LENGTH variable.  On errors,
+   return NULL and sets errno.  */
+char *
+read_file (const char *filename, size_t * length)
+{
+  return internal_read_file (filename, length, "r");
+}
+
+/* Open (on non-POSIX systems, in binary mode) and read the contents
+   of FILENAME, and return a newly allocated string with the content,
+   and set LENGTH to the length of the string.  The string is
+   zero-terminated, but the terminating zero character is not counted
+   in the LENGTH variable.  On errors, return NULL and sets errno.  */
+char *
+read_binary_file (const char *filename, size_t * length)
+{
+  return internal_read_file (filename, length, "rb");
+}
Index: lib/read-file.h
===================================================================
RCS file: lib/read-file.h
diff -N lib/read-file.h
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ lib/read-file.h     31 May 2006 13:25:27 -0000
@@ -0,0 +1,34 @@
+/* read-file.h -- read file contents into a string
+   Copyright (C) 2006 Free Software Foundation, Inc.
+   Written by Simon Josefsson.
+
+   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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifndef READ_FILE_H
+#define READ_FILE_H
+
+/* Get size_t.  */
+#include <stddef.h>
+
+/* Get FILE.  */
+#include <stdio.h>
+
+extern char *fread_file (FILE * stream, size_t * length);
+
+extern char *read_file (const char *filename, size_t * length);
+
+extern char *read_binary_file (const char *filename, size_t * length);
+
+#endif /* READ_FILE_H */
Index: m4/read-file.m4
===================================================================
RCS file: m4/read-file.m4
diff -N m4/read-file.m4
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ m4/read-file.m4     31 May 2006 13:25:27 -0000
@@ -0,0 +1,15 @@
+# read-file.m4 serial 1
+dnl Copyright (C) 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_READ_FILE],
+[
+  AC_LIBSOURCES([read-file.c, read-file.h])
+  AC_LIBOBJ([read-file])
+  gl_PREREQ_READ_FILE
+])
+
+# Prerequisites of lib/read-file.c.
+AC_DEFUN([gl_PREREQ_READ_FILE], [:])
Index: modules/read-file
===================================================================
RCS file: modules/read-file
diff -N modules/read-file
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ modules/read-file   31 May 2006 13:25:27 -0000
@@ -0,0 +1,24 @@
+Description:
+read_file() function: read the contents of a file into a string
+
+Files:
+lib/read-file.h
+lib/read-file.c
+m4/read-file.m4
+
+Depends-on:
+realloc
+
+configure.ac:
+gl_FUNC_READ_FILE
+
+Makefile.am:
+
+Include:
+"read-file.h"
+
+License:
+LGPL
+
+Maintainer:
+Simon Josefsson