Re: bug: when applying binary diffs, -p0 is ignored
Colin McCabe <cmccabe@alumni.cmu.edu> writes:
> I found a bug in git's handling of binary diff segments.
>
> When applying binary diffs using -p0, the prefix (or --strip) argument
> is ignored.
Thanks for a report. An ancient bug well spotted.
Perhaps this will help.
-- >8 --
Subject: apply: compute patch->def_name correctly under -p0
Back when "git apply" was written, we made sure that the user can skip more than the default number of path components (i.e. 1) by giving "-p<n>", but the logic for doing so was built around the notion of "we skip N slashes and stop". This obviously does not work well when running under -p0 where we do not want to skip any, but still want to skip SP/HT that separates the pathnames of preimage and postimage and want to reject absolute pathnames.
Stop using "stop_at_slash()", and instead introduce a new helper "skip_tree_prefix()" with similar logic but works correctly even for the -p0 case.
This is an ancient bug, but has been masked for a long time because most of the patches are text and have other clues to tell us the name of the preimage and the postimage.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
builtin/apply.c | 55 ++++++++++++++++++++++++++++++-------------------------
1 file changed, 30 insertions(+), 25 deletions(-)
diff --git i/builtin/apply.c w/builtin/apply.c
index 3bf71dc..4a511b3 100644
--- i/builtin/apply.c
+++ w/builtin/apply.c
@@ -1095,15 +1095,23 @@ static int gitdiff_unrecognized(const char *line, struct patch *patch)
return -1;
}
-static const char *stop_at_slash(const char *line, int llen)
+/*
+ * Skip p_value leading components from "line"; as we do not accept
+ * absolute paths, return NULL in that case.
+ */
+static const char *skip_tree_prefix(const char *line, int llen)
{
- int nslash = p_value;
+ int nslash;
int i;
+ if (!p_value)
+ return (llen && line[0] == '/') ? NULL : line;
+
+ nslash = p_value;
for (i = 0; i < llen; i++) {
int ch = line[i];
if (ch == '/' && --nslash <= 0)
- return &line[i];
+ return (i == 0) ? NULL : &line[i + 1];
}
return NULL;
}
@@ -1133,12 +1141,11 @@ static char *git_header_name(const char *line, int llen)
if (unquote_c_style(&first, line, &second))
goto free_and_fail1;
- /* advance to the first slash */
- cp = stop_at_slash(first.buf, first.len);
- /* we do not accept absolute paths */
- if (!cp || cp == first.buf)
+ /* strip the a/b prefix including trailing slash */
+ cp = skip_tree_prefix(first.buf, first.len);
+ if (!cp)
goto free_and_fail1;
- strbuf_remove(&first, 0, cp + 1 - first.buf);
+ strbuf_remove(&first, 0, cp - first.buf);
/*
* second points at one past closing dq of name.
@@ -1152,22 +1159,21 @@ static char *git_header_name(const char *line, int llen)
if (*second == '"') {
if (unquote_c_style(&sp, second, NULL))
goto free_and_fail1;
- cp = stop_at_slash(sp.buf, sp.len);
- if (!cp || cp == sp.buf)
+ cp = skip_tree_prefix(sp.buf, sp.len);
+ if (!cp)
goto free_and_fail1;
/* They must match, otherwise ignore */
- if (strcmp(cp + 1, first.buf))
+ if (strcmp(cp, first.buf))
goto free_and_fail1;
strbuf_release(&sp);
return strbuf_detach(&first, NULL);
}
/* unquoted second */
- cp = stop_at_slash(second, line + llen - second);
- if (!cp || cp == second)
+ cp = skip_tree_prefix(second, line + llen - second);
+ if (!cp)
goto free_and_fail1;
- cp++;
- if (line + llen - cp != first.len + 1 ||
+ if (line + llen - cp != first.len ||
memcmp(first.buf, cp, first.len))
goto free_and_fail1;
return strbuf_detach(&first, NULL);
@@ -1179,10 +1185,9 @@ static char *git_header_name(const char *line, int llen)
}
/* unquoted first name */
- name = stop_at_slash(line, llen);
- if (!name || name == line)
+ name = skip_tree_prefix(line, llen);
+ if (!name)
return NULL;
- name++;
/*
* since the first name is unquoted, a dq if exists must be
@@ -1196,10 +1201,9 @@ static char *git_header_name(const char *line, int llen)
if (unquote_c_style(&sp, second, NULL))
goto free_and_fail2;
- np = stop_at_slash(sp.buf, sp.len);
- if (!np || np == sp.buf)
+ np = skip_tree_prefix(sp.buf, sp.len);
+ if (!np)
goto free_and_fail2;
- np++;
len = sp.buf + sp.len - np;
if (len < second - name &&
@@ -1231,13 +1235,14 @@ static char *git_header_name(const char *line, int llen)
case '\n':
return NULL;
case '\t': case ' ':
- second = stop_at_slash(name + len, line_len - len);
+ if (!name[len + 1])
+ return NULL;
+ second = skip_tree_prefix(name + len + 1,
+ line_len - (len + 1));
if (!second)
return NULL;
- second++;
- if (second[len] == '\n' && !strncmp(name, second, len)) {
+ if (second[len] == '\n' && !strncmp(name, second, len))
return xmemdupz(name, len);
- }
}
}
}
