Add a dirent walker to the fileops API

Since at least MS have something like GetFirstDirEnt() and
GetNextDirEnt() (presumably with superior performance), we
can let MS hackers add support for a dirent walker using
that API instead, while we stick with the posix-style
readdir() calls.

Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

src/fileops.c

@@ -134,3 +134,65 @@ int gitfo_close_cached(gitfo_cache *ioc)
 
 	return gitfo_close(fd);
 }
+
+/**
+ * Walk a directory and run 'fn' for each encountered entry
+ * (except '.' and '..').
+ */
+int git_foreach_dirent(const char *wd, int (*fn)(void *, const char *), void *arg)
+{
+	char path[PATH_MAX];
+	size_t wd_len;
+	DIR *dir;
+	struct dirent *de;
+
+	if (!wd)
+		return GIT_ERROR;
+
+	wd_len = strlen(wd);
+	if (!wd_len || sizeof(path) < wd_len + 2)
+		return GIT_ERROR;
+
+	strcpy(path, wd);
+	while (path[wd_len - 1] == '/')
+		wd_len--;
+	path[wd_len++] = '/';
+	path[wd_len] = '\0';
+
+	dir = opendir(wd);
+	if (!dir)
+		return GIT_ERROR;
+
+	while ((de = readdir(dir))) {
+		size_t de_len;
+		int result;
+
+		/* always skip '.' and '..' */
+		if (de->d_name[0] == '.') {
+			if (de->d_name[1] == '\0')
+				continue;
+			if (de->d_name[1] == '.' && de->d_name[2] == '\0')
+				continue;
+		}
+
+		de_len = strlen(de->d_name);
+		if (sizeof(path) < wd_len + de_len + 1) {
+			closedir(dir);
+			return GIT_ERROR;
+		}
+
+		strcpy(path + wd_len, de->d_name);
+		result = fn(arg, path);
+		if (result < 0) {
+			closedir(dir);
+			return result;
+		}
+		if (result > 0) {
+			closedir(dir);
+			return result;
+		}
+	}
+
+	closedir(dir);
+	return GIT_SUCCESS;
+}

src/fileops.h

@@ -17,7 +17,9 @@
 #include <time.h>
 #include <stdlib.h>
 #include <string.h>
+#include <dirent.h>
 #include "errors.h"
+#include "git/fileops.h"
 
 typedef int git_file;
 typedef struct stat gitfo_statbuf;

src/git/fileops.h

@@ -0,0 +1,32 @@
+#ifndef INCLUDE_git_fileops_h__
+#define INCLUDE_git_fileops_h__
+
+/**
+ * @file git/fileops.h
+ * @brief Git platform agnostic filesystem operations
+ * @defgroup Git gitfiles
+ * @ingroup Git
+ * @{
+ */
+
+#include "common.h"
+GIT_BEGIN_DECL
+/**
+ * For each directory entry (except . and ..), run the function
+ * "fn", passing it "arg" as its first argument and the path to
+ * the entry as the second argument.
+ * @param dir The directory to walk
+ * @param fn The callback function to run for each entry in *dir.
+ *        "fn" may return >0 to signal "I'm done. Stop parsing and
+ *        return successfully" or <0 to signal an error.  All non-zero
+ *        return codes cause directory traversal to stop.
+ * @param arg The first argument that will be passed to 'fn'
+ * @return GIT_SUCCESS if all entries were successfully traversed,
+ *         otherwise the result of fn.
+ */
+GIT_EXTERN(int) git_foreach_dirent(const char *dir,
+			int (*fn)(void *, const char *), void *arg);
+
+/** @} */
+GIT_END_DECL
+#endif /* INCLUDE_git_fileops_h__ */