Refactor code from evdns into a new internal "read a file" function.

evutil.c

@@ -67,6 +67,7 @@
 #include <sys/timeb.h>
 #include <time.h>
 #endif
+#include <sys/stat.h>
 
 #include "event2/util.h"
 #include "util-internal.h"
@@ -76,6 +77,67 @@
 #include "strlcpy-internal.h"
 #include "ipv6-internal.h"
 
+/**
+   Read the contents of 'filename' into a newly allocated NUL-terminated
+   string.  Set *content_out to hold this string, and *len_out to hold its
+   length (not including the appended NUL).  If 'is_binary', open the file in
+   binary mode.
+
+   Returns 0 on success, -1 if the open fails, and -2 for all other failures.
+
+   Used internally only; may go away in a future version.
+ */
+int
+evutil_read_file(const char *filename, char **content_out, size_t *len_out,
+    int is_binary)
+{
+	int fd, r;
+	struct stat st;
+	char *mem;
+	size_t read_so_far=0;
+	int mode = O_RDONLY;
+
+	EVUTIL_ASSERT(content_out);
+	EVUTIL_ASSERT(len_out);
+	*content_out = NULL;
+	*len_out = 0;
+
+#ifdef O_BINARY
+	if (is_binary)
+		mode |= O_BINARY;
+#endif
+
+	fd = open(filename, mode);
+	if (fd < 0)
+		return -1;
+	if (fstat(fd, &st)) {
+		close(fd);
+		return -2;
+	}
+	mem = mm_malloc(st.st_size + 1);
+	if (!mem) {
+		close(fd);
+		return -2;
+	}
+	read_so_far = 0;
+	while ((r = read(fd, mem+read_so_far, st.st_size - read_so_far)) > 0) {
+		read_so_far += r;
+		if (read_so_far >= st.st_size)
+			break;
+		EVUTIL_ASSERT(read_so_far < st.st_size);
+	}
+	if (r < 0) {
+		close(fd);
+		mm_free(mem);
+		return -2;
+	}
+	mem[read_so_far] = 0;
+
+	*len_out = read_so_far;
+	*content_out = mem;
+	return 0;
+}
+
 int
 evutil_socketpair(int family, int type, int protocol, evutil_socket_t fd[2])
 {

util-internal.h

@@ -136,6 +136,8 @@ extern const char EVUTIL_TOLOWER_TABLE[];
 #define EVUTIL_UPCAST(ptr, type, field)				\
 	((type *)(((char*)(ptr)) - evutil_offsetof(type, field)))
 
+int evutil_read_file(const char *filename, char **content_out, size_t *len_out,
+    int is_binary);
 
 int evutil_socket_connect(evutil_socket_t *fd_ptr, struct sockaddr *sa, int socklen);