Change the name of real_path_internal to strbuf_realpath.  In addition
push the static strbuf up to its callers and instead take as a
parameter a pointer to a strbuf to use for the final result.

This change makes strbuf_realpath reentrant.

Signed-off-by: Brandon Williams <bmw...@google.com>
---
 abspath.c | 53 +++++++++++++++++++++++++----------------------------
 cache.h   |  2 ++
 2 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/abspath.c b/abspath.c
index 629201e48..a200d4220 100644
--- a/abspath.c
+++ b/abspath.c
@@ -57,21 +57,17 @@ static void get_next_component(struct strbuf *next, struct 
strbuf *remaining)
  * Return the real path (i.e., absolute path, with symlinks resolved
  * and extra slashes removed) equivalent to the specified path.  (If
  * you want an absolute path but don't mind links, use
- * absolute_path().)  The return value is a pointer to a static
- * buffer.
+ * absolute_path().)  Places the resolved realpath in the provided strbuf.
  *
  * The directory part of path (i.e., everything up to the last
  * dir_sep) must denote a valid, existing directory, but the last
  * component need not exist.  If die_on_error is set, then die with an
  * informative error message if there is a problem.  Otherwise, return
  * NULL on errors (without generating any output).
- *
- * If path is our buffer, then return path, as it's already what the
- * user wants.
  */
-static const char *real_path_internal(const char *path, int die_on_error)
+char *strbuf_realpath(struct strbuf *resolved, const char *path,
+                     int die_on_error)
 {
-       static struct strbuf resolved = STRBUF_INIT;
        struct strbuf remaining = STRBUF_INIT;
        struct strbuf next = STRBUF_INIT;
        struct strbuf symlink = STRBUF_INIT;
@@ -79,10 +75,6 @@ static const char *real_path_internal(const char *path, int 
die_on_error)
        int num_symlinks = 0;
        struct stat st;
 
-       /* We've already done it */
-       if (path == resolved.buf)
-               return path;
-
        if (!*path) {
                if (die_on_error)
                        die("The empty string is not a valid path");
@@ -90,16 +82,16 @@ static const char *real_path_internal(const char *path, int 
die_on_error)
                        goto error_out;
        }
 
-       strbuf_reset(&resolved);
+       strbuf_reset(resolved);
 
        if (is_absolute_path(path)) {
                /* absolute path; start with only root as being resolved */
                int offset = offset_1st_component(path);
-               strbuf_add(&resolved, path, offset);
+               strbuf_add(resolved, path, offset);
                strbuf_addstr(&remaining, path + offset);
        } else {
                /* relative path; can use CWD as the initial resolved path */
-               if (strbuf_getcwd(&resolved)) {
+               if (strbuf_getcwd(resolved)) {
                        if (die_on_error)
                                die_errno("unable to get current working 
directory");
                        else
@@ -118,21 +110,21 @@ static const char *real_path_internal(const char *path, 
int die_on_error)
                        continue; /* '.' component */
                } else if (next.len == 2 && !strcmp(next.buf, "..")) {
                        /* '..' component; strip the last path component */
-                       strip_last_component(&resolved);
+                       strip_last_component(resolved);
                        continue;
                }
 
                /* append the next component and resolve resultant path */
-               if (!is_dir_sep(resolved.buf[resolved.len - 1]))
-                       strbuf_addch(&resolved, '/');
-               strbuf_addbuf(&resolved, &next);
+               if (!is_dir_sep(resolved->buf[resolved->len - 1]))
+                       strbuf_addch(resolved, '/');
+               strbuf_addbuf(resolved, &next);
 
-               if (lstat(resolved.buf, &st)) {
+               if (lstat(resolved->buf, &st)) {
                        /* error out unless this was the last component */
                        if (errno != ENOENT || remaining.len) {
                                if (die_on_error)
                                        die_errno("Invalid path '%s'",
-                                                 resolved.buf);
+                                                 resolved->buf);
                                else
                                        goto error_out;
                        }
@@ -150,12 +142,12 @@ static const char *real_path_internal(const char *path, 
int die_on_error)
                                        goto error_out;
                        }
 
-                       len = strbuf_readlink(&symlink, resolved.buf,
+                       len = strbuf_readlink(&symlink, resolved->buf,
                                              st.st_size);
                        if (len < 0) {
                                if (die_on_error)
                                        die_errno("Invalid symlink '%s'",
-                                                 resolved.buf);
+                                                 resolved->buf);
                                else
                                        goto error_out;
                        }
@@ -163,8 +155,8 @@ static const char *real_path_internal(const char *path, int 
die_on_error)
                        if (is_absolute_path(symlink.buf)) {
                                /* absolute symlink; set resolved to root */
                                int offset = offset_1st_component(symlink.buf);
-                               strbuf_reset(&resolved);
-                               strbuf_add(&resolved, symlink.buf, offset);
+                               strbuf_reset(resolved);
+                               strbuf_add(resolved, symlink.buf, offset);
                                strbuf_remove(&symlink, 0, offset);
                        } else {
                                /*
@@ -172,7 +164,7 @@ static const char *real_path_internal(const char *path, int 
die_on_error)
                                 * strip off the last component since it will
                                 * be replaced with the contents of the symlink
                                 */
-                               strip_last_component(&resolved);
+                               strip_last_component(resolved);
                        }
 
                        /*
@@ -192,24 +184,29 @@ static const char *real_path_internal(const char *path, 
int die_on_error)
                }
        }
 
-       retval = resolved.buf;
+       retval = resolved->buf;
 
 error_out:
        strbuf_release(&remaining);
        strbuf_release(&next);
        strbuf_release(&symlink);
 
+       if (!retval)
+               strbuf_reset(resolved);
+
        return retval;
 }
 
 const char *real_path(const char *path)
 {
-       return real_path_internal(path, 1);
+       static struct strbuf realpath = STRBUF_INIT;
+       return strbuf_realpath(&realpath, path, 1);
 }
 
 const char *real_path_if_valid(const char *path)
 {
-       return real_path_internal(path, 0);
+       static struct strbuf realpath = STRBUF_INIT;
+       return strbuf_realpath(&realpath, path, 0);
 }
 
 /*
diff --git a/cache.h b/cache.h
index a50a61a19..7a8129403 100644
--- a/cache.h
+++ b/cache.h
@@ -1064,6 +1064,8 @@ static inline int is_absolute_path(const char *path)
        return is_dir_sep(path[0]) || has_dos_drive_prefix(path);
 }
 int is_directory(const char *);
+char *strbuf_realpath(struct strbuf *resolved, const char *path,
+                     int die_on_error);
 const char *real_path(const char *path);
 const char *real_path_if_valid(const char *path);
 const char *absolute_path(const char *path);
-- 
2.11.0.390.gc69c2f50cf-goog

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