Use git_buf for path storage instead of stack-based buffers

This converts virtually all of the places that allocate GIT_PATH_MAX
buffers on the stack for manipulating paths to use git_buf objects
instead.  The patch is pretty careful not to touch the public API
for libgit2, so there are a few places that still use GIT_PATH_MAX.

This extends and changes some details of the git_buf implementation
to add a couple of extra functions and to make error handling easier.

This includes serious alterations to all the path.c functions, and
several of the fileops.c ones, too.  Also, there are a number of new
functions that parallel existing ones except that use a git_buf
instead of a stack-based buffer (such as git_config_find_global_r
that exists alongsize git_config_find_global).

This also modifies the win32 version of p_realpath to allocate whatever
buffer size is needed to accommodate the realpath instead of hardcoding
a GIT_PATH_MAX limit, but that change needs to be tested still.

1 files changed, 24 insertions, 7 deletions

diff --git a/src/fileops.h b/src/fileops.h
index e1a59f633..df135d0db 100644
--- a/src/fileops.h
+++ b/src/fileops.h
@@ -28,6 +28,7 @@ typedef struct { /* file io buffer */
 extern int git_futils_readbuffer(git_fbuffer *obj, const char *path);
 extern int git_futils_readbuffer_updated(git_fbuffer *obj, const char *path, time_t *mtime, int *updated);
 extern void git_futils_freebuffer(git_fbuffer *obj);
+extern void git_futils_fbuffer_rtrim(git_fbuffer *obj);
 
 /**
  * File utils
@@ -72,9 +73,25 @@ extern int git_futils_isdir(const char *path);
 extern int git_futils_isfile(const char *path);
 
 /**
+ * Check if the given path contains the given subdirectory.
+ *
+ * If `append_if_exists` is true, then the subdir will be appended to the
+ * parent path if it does exists.
+ */
+extern int git_futils_contains_dir(git_buf *parent, const char *subdir, int append_if_exists);
+
+/**
+ * Check if the given path contains the given file
+ *
+ * If `append_if_exists` is true, then the filename will be appended to the
+ * parent path if it does exists.
+ */
+extern int git_futils_contains_file(git_buf *parent, const char *file, int append_if_exists);
+
+/**
  * Create a path recursively
  */
-extern int git_futils_mkdir_r(const char *path, const mode_t mode);
+extern int git_futils_mkdir_r(const char *path, const char *base, const mode_t mode);
 
 /**
  * Create all the folders required to contain
@@ -85,9 +102,11 @@ extern int git_futils_mkpath2file(const char *path, const mode_t mode);
 extern int git_futils_rmdir_r(const char *path, int force);
 
 /**
- * Create and open a temporary file with a `_git2_` suffix
+ * Create and open a temporary file with a `_git2_` suffix.
+ * Writes the filename into path_out.
+ * @return On success, an open file descriptor, else an error code < 0.
  */
-extern int git_futils_mktmp(char *path_out, const char *filename);
+extern int git_futils_mktmp(git_buf *path_out, const char *filename);
 
 /**
  * Move a file on the filesystem, create the
@@ -133,16 +152,14 @@ extern void git_futils_mmap_free(git_map *map);
  *
  * @param pathbuf buffer the function reads the initial directory
  * 		path from, and updates with each successive entry's name.
- * @param pathmax maximum allocation of pathbuf.
  * @param fn function to invoke with each entry. The first arg is
  *		the input state and the second arg is pathbuf. The function
  *		may modify the pathbuf, but only by appending new text.
  * @param state to pass to fn as the first arg.
  */
 extern int git_futils_direach(
-	char *pathbuf,
-	size_t pathmax,
-	int (*fn)(void *, char *),
+	git_buf *pathbuf,
+	int (*fn)(void *, git_buf *),
 	void *state);
 
 extern int git_futils_cmp_path(const char *name1, int len1, int isdir1,