Signed-off-by: Alex Riesen <raa.lkml@xxxxxxxxx>
---
This will be used by the following patch. I actually already have sent
this one in, as suggestion for some problem back then. It is a bit
generic, so it gets its own patch.
cache.h | 2 ++
path.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 61 insertions(+), 0 deletions(-)
diff --git a/cache.h b/cache.h
index 054f106..25ce5da 100644
--- a/cache.h
+++ b/cache.h
@@ -383,6 +383,8 @@ static inline int is_absolute_path(const char *path)
return path[0] == '/';
}
const char *make_absolute_path(const char *path);
+/* Returns the analog of "cd path" from a directory "cwd" */
+extern char *pathexpand(const char *cwd, const char *path);
/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
extern int sha1_object_info(const unsigned char *, unsigned long *);
diff --git a/path.c b/path.c
index 4260952..8231cd8 100644
--- a/path.c
+++ b/path.c
@@ -353,3 +353,62 @@ const char *make_absolute_path(const char *path)
return buf;
}
+
+/*
+ * Returns the analog of "cd path" from a directory "cwd".
+ * The root is defined as empty path (instead of "/")
+ * An attempt to go past the root (with "..") leaves the path at root.
+ * The cwd is not expanded.
+ */
+char *pathexpand(const char *cwd, const char *path)
+{
+ static const char SEP[] = "/";
+ if (!*path) /* empty path -> "." (don't move) */
+ path = ".";
+ if (!cwd || !*cwd || *SEP == *path) /* no cwd, or path begins with "/" */
+ cwd = "";
+
+ while (*cwd && *SEP == *cwd)
+ ++cwd;
+
+ size_t len = strlen(cwd);
+ char *out = malloc(len + 1 + strlen(path) + 1);
+ char *p = strcpy(out, cwd) + len;
+
+ for (; *path; ++path)
+ {
+ char *pl;
+ if (p > out && p[-1] != *SEP)
+ *p++ = *SEP;
+ pl = p;
+ while (*path && *SEP != *path)
+ *p++ = *path++;
+ *p = '\0';
+ /* ..."//"... */
+ if (p == pl)
+ ; /* just ignore */
+ /* ..."/./"... */
+ else if ( p - pl == 1 && '.' == *pl )
+ --p; /* just ignore */
+ /* ..."/../"... */
+ else if ( p - pl == 2 && '.' == pl[0] && '.' == pl[1] )
+ {
+ /* drop the last element of the resulting path */
+ if (pl > out && --pl > out)
+ for (--pl; pl > out && *SEP != *pl; --pl)
+ ;
+ p = pl > out ? ++pl: out;
+ }
+ /* ..."/path/"... */
+ else if (*path)
+ *p++ = *path; /* just add the separator */
+
+ if (!*path)
+ break;
+ }
+ if (p > out+1 && *SEP == p[-1])
+ --p;
+ *p = '\0';
+ return out;
+}
+
--
1.5.4.rc0.86.g30f5
-
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