Implement textfile writing support

1 files changed, 148 insertions, 12 deletions

diff --git a/common/textfile.c b/common/textfile.c
index 6f84cfa9..0bda2a94 100644
--- a/common/textfile.c
+++ b/common/textfile.c
@@ -40,51 +40,186 @@
 #include <sys/stat.h>
 #include <sys/mman.h>
 
+static int write_key_value(const int fd, const char *key, const char *value)
+{
+	char *str;
+	int size, err = 0;
+
+	size = strlen(key) + strlen(value) + 2;
+
+	str = malloc(size);
+	if (!str)
+		return ENOMEM;
+
+	sprintf(str, "%s %s\n", key, value);
+
+	if (write(fd, str, size) < 0)
+		err = errno;
+
+	free(str);
+
+	return err;
+}
+
+int textfile_put(const char *pathname, const char *key, const char *value)
+{
+	struct stat st;
+	char *map, *off, *end, *str;
+	off_t size, pos; size_t base, len;
+	int fd, err = 0;
+
+	fd = open(pathname, O_RDWR);
+	if (fd < 0)
+		return -errno;
+
+	if (flock(fd, LOCK_EX) < 0) {
+		err = errno;
+		goto close;
+	}
+
+	if (fstat(fd, &st) < 0) {
+		err = errno;
+		goto unlock;
+	}
+
+	size = st.st_size;
+
+	if (!size) {
+		pos = lseek(fd, size, SEEK_SET);
+		err = write_key_value(fd, key, value);
+		goto unlock;
+	}
+
+	map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (map == MAP_FAILED) {
+		err = errno;
+		goto unlock;
+	}
+
+	off = strstr(map, key);
+	if (!off) {
+		munmap(map, size);
+		pos = lseek(fd, size, SEEK_SET);
+		err = write_key_value(fd, key, value);
+		goto unlock;
+	}
+
+	if (off > map) {
+		while (*(off - 1) != '\r' && *(off - 1) != '\n') {
+			off = strstr(off, key);
+			if (!off) {
+				munmap(map, size);
+				pos = lseek(fd, size, SEEK_SET);
+				err = write_key_value(fd, key, value);
+				goto unlock;
+			}
+		}
+	}
+
+	base = off - map;
+
+	end = strpbrk(off, "\r\n");
+	if (!end) {
+		err = EILSEQ;
+		goto unmap;
+	}
+
+	len = strspn(end, "\r\n");
+	end += len;
+
+	len = size - (end - map);
+
+	str = malloc(len);
+	if (!str) {
+		err = errno;
+		goto unmap;
+	}
+
+	memcpy(str, end, len);
+	munmap(map, size);
+
+	ftruncate(fd, base);
+	pos = lseek(fd, base, SEEK_SET);
+
+	write_key_value(fd, key, value);
+	write(fd, str, len);
+
+	free(str);
+
+	goto unlock;
+
+unmap:
+	munmap(map, size);
+
+unlock:
+	flock(fd, LOCK_UN);
+
+close:
+	close(fd);
+	errno = err;
+
+	return -err;
+}
+
 char *textfile_get(const char *pathname, const char *key)
 {
 	struct stat st;
 	char *map, *off, *end, *str = NULL;
 	off_t size; size_t len;
-	int fd;
+	int fd, err = 0;
 
 	fd = open(pathname, O_RDONLY);
 	if (fd < 0)
 		return NULL;
 
-	if (flock(fd, LOCK_SH) < 0)
+	if (flock(fd, LOCK_SH) < 0) {
+		err = errno;
 		goto close;
+	}
 
-	if (fstat(fd, &st) < 0)
+	if (fstat(fd, &st) < 0) {
+		err = errno;
 		goto unlock;
+	}
 
 	size = st.st_size;
 
-	map = mmap(0, size, PROT_READ, MAP_SHARED, fd, 0);
-	if (map == MAP_FAILED)
-		goto close;
+	map = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
+	if (map == MAP_FAILED) {
+		err = errno;
+		goto unlock;
+	}
 
 	off = strstr(map, key);
-	if (!off)
+	if (!off) {
+		err = EILSEQ;
 		goto unmap;
+	}
 
 	if (off > map) {
 		while (*(off - 1) != '\r' && *(off - 1) != '\n') {
-			off = strstr(map, key);
-			if (!off)
+			off = strstr(off, key);
+			if (!off) {
+				err = EILSEQ;
 				goto unmap;
+			}
 		}
 	}
 
 	end = strpbrk(off, "\r\n");
-	if (!end)
+	if (!end) {
+		err = EILSEQ;
 		goto unmap;
+	}
 
 	len = strlen(key);
 	str = malloc(end - off - len);
-	memset(str, 0, end - off - len);
-	if (!str)
+	if (!str) {
+		err = EILSEQ;
 		goto unmap;
+	}
 
+	memset(str, 0, end - off - len);
 	strncpy(str, off + len + 1, end - off - len - 1);
 
 unmap:
@@ -95,6 +230,7 @@ unlock:
 
 close:
 	close(fd);
+	errno = err;
 
 	return str;
 }