[PATCH v2 1/2] abspath: add a function to resolve paths with missing components
- From
brian m. carlson <sandals@crustytoothpaste.net>
- Date
- Oct 9, 2020, 19:15 UTC
- Message-ID
- <20201009191511.267461-2-sandals@crustytoothpaste.net>
- In-Reply-To
- <20201009191511.267461-1-sandals@crustytoothpaste.net>
We'd like to canonicalize paths such that we can preserve any number of trailing components that may be missing. Let's add a function to do that that calls strbuf_realpath to find the canonical path for the portion we do have and then append the missing part. We adjust strip_last_component to return us the component it has stripped and use that to help us accumulate the missing part.
Note that it is intentional that we invoke strbuf_realpath here, repeatedly if necessary, because on Windows that function is replaced with a version that uses the proper system semantics for canonicalization. Trying to adjust strbuf_realpath to perform this kind of canonicalization with an additional option would fail to work properly on Windows. The present approach is equivalent to strbuf_realpath for cases where the path exists, and the only other cases where we will use this function the additional overhead of multiple invocations is not significant.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> --- abspath.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++---- cache.h | 1 + 2 files changed, 47 insertions(+), 4 deletions(-)
diff --git a/abspath.c b/abspath.c index 6f15a418bb..092bb33b64 100644 --- a/abspath.c +++ b/abspath.c @@ -11,8 +11,12 @@ int is_directory(const char *path) return (!stat(path, &st) && S_ISDIR(st.st_mode)); } -/* removes the last path component from 'path' except if 'path' is root */ -static void strip_last_component(struct strbuf *path) +/* + * Removes the last path component from 'path' except if 'path' is root. + * + * If last is not NULL, the last path component is copied to last. + */ +static void strip_last_component(struct strbuf *path, struct strbuf *last) { size_t offset = offset_1st_component(path->buf); size_t len = path->len; @@ -20,6 +24,10 @@ static void strip_last_component(struct strbuf *path) /* Find start of the last component */ while (offset < len && !is_dir_sep(path->buf[len - 1])) len--; + + if (last) + strbuf_addstr(last, path->buf + len); + /* Skip sequences of multiple path-separators */ while (offset < len && is_dir_sep(path->buf[len - 1])) len--; @@ -118,7 +126,7 @@ char *strbuf_realpath(struct strbuf *resolved, const char *path, continue; /* '.' component */ } else if (next.len == 2 && !strcmp(next.buf, "..")) { /* '..' component; strip the last path component */ - strip_last_component(resolved); + strip_last_component(resolved, NULL); continue; } @@ -169,7 +177,7 @@ char *strbuf_realpath(struct strbuf *resolved, const char *path, * strip off the last component since it will * be replaced with the contents of the symlink */ - strip_last_component(resolved); + strip_last_component(resolved, NULL); } /* @@ -202,6 +210,40 @@ char *strbuf_realpath(struct strbuf *resolved, const char *path, return retval; } +/* + * Like strbuf_realpath, but trailing components which do not exist are copied + * through. + */ +char *strbuf_realpath_missing(struct strbuf *resolved, const char *path) +{ + struct strbuf remaining = STRBUF_INIT; + struct strbuf trailing = STRBUF_INIT; + struct strbuf component = STRBUF_INIT; + + strbuf_addstr(&remaining, path); + + while (remaining.len) { + if (strbuf_realpath(resolved, remaining.buf, 0)) { + strbuf_addbuf(resolved, &trailing); + + strbuf_release(&component); + strbuf_release(&remaining); + strbuf_release(&trailing); + + return resolved->buf; + } + strip_last_component(&remaining, &component); + strbuf_insertstr(&trailing, 0, "/"); + strbuf_insertstr(&trailing, 1, component.buf); + strbuf_reset(&component); + } + + strbuf_release(&component); + strbuf_release(&remaining); + strbuf_release(&trailing); + return NULL; +} + char *real_pathdup(const char *path, int die_on_error) { struct strbuf realpath = STRBUF_INIT; diff --git a/cache.h b/cache.h index c0072d43b1..e1e17e108e 100644 --- a/cache.h +++ b/cache.h @@ -1320,6 +1320,7 @@ static inline int is_absolute_path(const char *path) int is_directory(const char *); char *strbuf_realpath(struct strbuf *resolved, const char *path, int die_on_error); +char *strbuf_realpath_missing(struct strbuf *resolved, const char *path); char *real_pathdup(const char *path, int die_on_error); const char *absolute_path(const char *path); char *absolute_pathdup(const char *path);