[PATCH 1/3] config: read full file content before parsing

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

config files are usually short enough that we can read in full. This
allows the parser to parse in-memory config, for example from a blob.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 config.c |   62 +++++++++++++++++++++++++++++++++++---------------------------
 1 files changed, 35 insertions(+), 27 deletions(-)

diff --git a/config.c b/config.c
index f138c34..c8bf46f 100644
--- a/config.c
+++ b/config.c
@@ -12,7 +12,8 @@
 
 #define MAXNAME (256)
 
-static FILE *config_file;
+static char *config_file;
+static size_t config_file_size, config_file_pos;
 static const char *config_file_name;
 static int config_linenr;
 static int config_file_eof;
@@ -108,28 +109,26 @@ int git_config_parse_environment(void) {
 
 static int get_next_char(void)
 {
-	int c;
-	FILE *f;
+	size_t unread = config_file_size - config_file_pos;
+
+	if (config_file == NULL)
+		return '\n';
 
-	c = '\n';
-	if ((f = config_file) != NULL) {
-		c = fgetc(f);
+	if (unread) {
+		char c = config_file[config_file_pos++];
 		if (c == '\r') {
 			/* DOS like systems */
-			c = fgetc(f);
-			if (c != '\n') {
-				ungetc(c, f);
-				c = '\r';
-			}
+			if (unread > 1 &&
+			    config_file[config_file_pos] == '\n')
+				c = config_file[config_file_pos++];
 		}
 		if (c == '\n')
 			config_linenr++;
-		if (c == EOF) {
-			config_file_eof = 1;
-			c = '\n';
-		}
+		return c;
 	}
-	return c;
+
+	config_file_eof = 1;
+	return '\n';
 }
 
 static char *parse_value(void)
@@ -786,19 +785,27 @@ int git_default_config(const char *var, const char *value, void *dummy)
 
 int git_config_from_file(config_fn_t fn, const char *filename, void *data)
 {
-	int ret;
-	FILE *f = fopen(filename, "r");
+	struct stat st;
+	int ret = -1, fd;
+
+	if (lstat(filename, &st))
+		return -1;
+	fd = open(filename, O_RDONLY);
+	if (fd == -1)
+		return -1;
 
-	ret = -1;
-	if (f) {
-		config_file = f;
+	config_file = xmalloc(st.st_size);
+	if (read_in_full(fd, config_file, st.st_size) == st.st_size) {
+		config_file_pos = 0;
+		config_file_size = st.st_size;
 		config_file_name = filename;
 		config_linenr = 1;
 		config_file_eof = 0;
 		ret = git_parse_file(fn, data);
-		fclose(f);
-		config_file_name = NULL;
 	}
+	close(fd);
+	free(config_file);
+	config_file_name = NULL;
 	return ret;
 }
 
@@ -921,7 +928,7 @@ static int store_aux(const char *key, const char *value, void *cb)
 				return 1;
 			}
 
-			store.offset[store.seen] = ftell(config_file);
+			store.offset[store.seen] = config_file_pos;
 			store.seen++;
 		}
 		break;
@@ -948,19 +955,19 @@ static int store_aux(const char *key, const char *value, void *cb)
 		 * Do not increment matches: this is no match, but we
 		 * just made sure we are in the desired section.
 		 */
-		store.offset[store.seen] = ftell(config_file);
+		store.offset[store.seen] = config_file_pos;
 		/* fallthru */
 	case SECTION_END_SEEN:
 	case START:
 		if (matches(key, value)) {
-			store.offset[store.seen] = ftell(config_file);
+			store.offset[store.seen] = config_file_pos;
 			store.state = KEY_SEEN;
 			store.seen++;
 		} else {
 			if (strrchr(key, '.') - key == store.baselen &&
 			      !strncmp(key, store.key, store.baselen)) {
 					store.state = SECTION_SEEN;
-					store.offset[store.seen] = ftell(config_file);
+					store.offset[store.seen] = config_file_pos;
 			}
 		}
 	}
@@ -1380,6 +1387,7 @@ int git_config_rename_section(const char *old_name, const char *new_name)
 {
 	int ret = 0, remove = 0;
 	char *config_filename;
+	FILE *config_file;
 	struct lock_file *lock = xcalloc(sizeof(struct lock_file), 1);
 	int out_fd;
 	char buf[1024];
-- 
1.7.3.3.476.g893a9