Add a file reading routine along with an io buffer type

In particular, the gitfo_read_file() routine can be used to slurp
the complete file contents into an gitfo_buf structure. The buffer
content will be allocated by malloc() and may be released by the
gitfo_free_buf() routine. The io buffer type can be initialised
on the stack with the GITFO_BUF_INIT macro.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

src/common.h

@@ -4,6 +4,7 @@
 #include "cc-compat.h"
 #include "util.h"
 #include "errors.h"
+#include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <unistd.h>

src/fileops.c

@@ -49,6 +49,43 @@ off_t gitfo_size(git_file fd)
 	return sb.st_size;
 }
 
+int gitfo_read_file(gitfo_buf *obj, const char *path)
+{
+	git_file fd;
+	off_t len;
+	void *buff;
+
+	assert(obj && path && *path);
+
+	if ((fd = gitfo_open(path, O_RDONLY)) < 0)
+		return GIT_ERROR;  /* TODO: error handling */
+
+	if (((len = gitfo_size(fd)) < 0) || ((buff = malloc(len)) == NULL)) {
+		gitfo_close(fd);
+		return GIT_ERROR;  /* TODO: error handling */
+	}
+
+	if (gitfo_read(fd, buff, len) < 0) {
+		gitfo_close(fd);
+		free(buff);
+		return GIT_ERROR;  /* TODO: error handling */
+	}
+
+	gitfo_close(fd);
+
+	obj->data = buff;
+	obj->len  = len;
+
+	return GIT_SUCCESS;
+}
+
+void gitfo_free_buf(gitfo_buf *obj)
+{
+	assert(obj);
+	free(obj->data);
+	obj->data = NULL;
+}
+
 /* cached diskio */
 struct gitfo_cache {
 	git_file fd;

src/fileops.h

@@ -21,10 +21,18 @@
 #include "errors.h"
 #include "git/fileops.h"
 
+#define GITFO_BUF_INIT {NULL, 0}
+
 typedef int git_file;
 typedef struct stat gitfo_statbuf;
 typedef struct gitfo_cache gitfo_cache;
 
+typedef struct {  /* file io buffer  */
+	void *data;  /* data bytes   */
+	size_t len;  /* data length  */
+} gitfo_buf;
+
+
 #define gitfo_open(path, flags) open(path, flags)
 #define gitfo_close(fd) close(fd)
 
@@ -37,6 +45,9 @@ extern off_t gitfo_size(git_file fd);
 #define gitfo_stat(path, buf) stat(path, buf)
 #define gitfo_fsync(fd) fsync(fd)
 
+extern int gitfo_read_file(gitfo_buf *obj, const char *path);
+extern void gitfo_free_buf(gitfo_buf *obj);
+
 extern gitfo_cache *gitfo_enable_caching(git_file fd, size_t cache_size);
 extern int gitfo_write_cached(gitfo_cache *ioc, void *buf, size_t len);
 extern int gitfo_flush_cached(gitfo_cache *ioc);