Add utility function to iterate over lines in a file

Signed-off-by: David Oberhollenzer <goliath@infraroot.at>

include/util/util.h

@@ -11,4 +11,9 @@ ssize_t read_retry(int fd, void *buffer, size_t size);
 
 int mkdir_p(const char *path);
 
+typedef int (*linecb_t)(void *usr, const char *filename,
+			size_t linenum, char *line);
+
+int foreach_line_in_file(const char *filename, void *usr, linecb_t fun);
+
 #endif /* UTIL_H */

lib/Makemodule.am

@@ -3,6 +3,7 @@ libutil_a_SOURCES += lib/util/write_retry.c lib/util/read_retry.c
 libutil_a_SOURCES += lib/util/canonicalize_name.c
 libutil_a_SOURCES += include/util/util.h include/util/input_file.h
 libutil_a_SOURCES += include/util/hashtable.h lib/util/hashtable.c
+libutil_a_SOURCES += lib/util/fileproc.c
 
 libfilelist_a_SOURCES = lib/filelist/dump_toc.c lib/filelist/image_entry.c
 libfilelist_a_SOURCES += lib/filelist/image_entry_sort.c

lib/util/fileproc.c

@@ -0,0 +1,61 @@
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <errno.h>
+
+#include "util/util.h"
+
+int foreach_line_in_file(const char *filename, void *usr, linecb_t fun)
+{
+	FILE *f = fopen(filename, "r");
+	char *line = NULL, *ptr;
+	size_t n, lineno = 1;
+	ssize_t ret;
+
+	if (f == NULL) {
+		perror(filename);
+		return -1;
+	}
+
+	for (;;) {
+		free(line);
+
+		line = NULL;
+		errno = 0;
+		n = 0;
+		ret = getline(&line, &n, f);
+
+		if (ret < 0) {
+			if (errno == 0) {
+				ret = 0;
+				break;
+			}
+			perror(filename);
+			break;
+		}
+
+		for (ptr = line; isspace(*ptr); ++ptr)
+			;
+
+		if (ptr != line)
+			memmove(line, ptr, strlen(ptr) + 1);
+
+		ptr = line + strlen(line);
+		while (ptr > line && isspace(ptr[-1]))
+			--ptr;
+		*ptr = '\0';
+
+		if (*line == '\0')
+			continue;
+
+		if (fun(usr, filename, lineno++, line)) {
+			ret = -1;
+			break;
+		}
+	}
+
+	free(line);
+	fclose(f);
+	return ret;
+}