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path.c: refactor relative_path(), not only strip prefix

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Original design of relative_path() is simple, just strip the prefix
(*base) from the absolute path (*abs).

In most cases, we need a real relative path, such as: ../foo,
../../bar.  That's why there is another reimplementation
(path_relative()) in quote.c.

Borrow some codes from path_relative() in quote.c to refactor
relative_path() in path.c, so that it could return real relative
path, and user can reuse this function without reimplementing
his/her own.  The function path_relative() in quote.c will be
substituted, and I would use the new relative_path() function when
implementing the interactive git-clean later.

Different results for relative_path() before and after this refactor:

    abs path  base path  relative (original)  relative (refactor)
    ========  =========  ===================  ===================
    /a/b      /a/b       .                    ./
    /a/b/     /a/b       .                    ./
    /a        /a/b/      /a                   ../
    /         /a/b/      /                    ../../
    /a/c      /a/b/      /a/c                 ../c
    /x/y      /a/b/      /x/y                 ../../x/y

    a/b/      a/b/       .                    ./
    a/b/      a/b        .                    ./
    a         a/b        a                    ../
    x/y       a/b/       x/y                  ../../x/y
    a/c       a/b        a/c                  ../c

    (empty)   (null)     (empty)              ./
    (empty)   (empty)    (empty)              ./
    (empty)   /a/b       (empty)              ./
    (null)    (null)     (null)               ./
    (null)    (empty)    (null)               ./
    (null)    /a/b       (segfault)           ./

You may notice that return value "." has been changed to "./".
It is because:

 * Function quote_path_relative() in quote.c will show the relative
   path as "./" if abs(in) and base(prefix) are the same.

 * Function relative_path() is called only once (in setup.c), and
   it will be OK for the return value as "./" instead of ".".

Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jiang Xin
2013-06-25 23:53:43 +08:00
committed by Junio C Hamano
parent 203439b284
commit e02ca72f70
5 changed files with 111 additions and 51 deletions
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112
path.c
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@ -441,42 +441,100 @@ int adjust_shared_perm(const char *path)
return 0;
}
const char *relative_path(const char *abs, const char *base)
/*
* Give path as relative to prefix.
*
* The strbuf may or may not be used, so do not assume it contains the
* returned path.
*/
const char *relative_path(const char *in, const char *prefix,
struct strbuf *sb)
{
static char buf[PATH_MAX + 1];
int in_len = in ? strlen(in) : 0;
int prefix_len = prefix ? strlen(prefix) : 0;
int in_off = 0;
int prefix_off = 0;
int i = 0, j = 0;
if (!base || !base[0])
return abs;
while (base[i]) {
if (is_dir_sep(base[i])) {
if (!is_dir_sep(abs[j]))
return abs;
while (is_dir_sep(base[i]))
if (!in_len)
return "./";
else if (!prefix_len)
return in;
while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
if (is_dir_sep(prefix[i])) {
while (is_dir_sep(prefix[i]))
i++;
while (is_dir_sep(abs[j]))
while (is_dir_sep(in[j]))
j++;
prefix_off = i;
in_off = j;
} else {
i++;
j++;
}
}
if (
/* "prefix" seems like prefix of "in" */
i >= prefix_len &&
/*
* but "/foo" is not a prefix of "/foobar"
* (i.e. prefix not end with '/')
*/
prefix_off < prefix_len) {
if (j >= in_len) {
/* in="/a/b", prefix="/a/b" */
in_off = in_len;
} else if (is_dir_sep(in[j])) {
/* in="/a/b/c", prefix="/a/b" */
while (is_dir_sep(in[j]))
j++;
in_off = j;
} else {
/* in="/a/bbb/c", prefix="/a/b" */
i = prefix_off;
}
} else if (
/* "in" is short than "prefix" */
j >= in_len &&
/* "in" not end with '/' */
in_off < in_len) {
if (is_dir_sep(prefix[i])) {
/* in="/a/b", prefix="/a/b/c/" */
while (is_dir_sep(prefix[i]))
i++;
in_off = in_len;
}
}
in += in_off;
in_len -= in_off;
if (i >= prefix_len) {
if (!in_len)
return "./";
else
return in;
}
strbuf_reset(sb);
strbuf_grow(sb, in_len);
while (i < prefix_len) {
if (is_dir_sep(prefix[i])) {
strbuf_addstr(sb, "../");
while (is_dir_sep(prefix[i]))
i++;
continue;
} else if (abs[j] != base[i]) {
return abs;
}
i++;
j++;
}
if (
/* "/foo" is a prefix of "/foo" */
abs[j] &&
/* "/foo" is not a prefix of "/foobar" */
!is_dir_sep(base[i-1]) && !is_dir_sep(abs[j])
)
return abs;
while (is_dir_sep(abs[j]))
j++;
if (!abs[j])
strcpy(buf, ".");
else
strcpy(buf, abs + j);
return buf;
if (!is_dir_sep(prefix[prefix_len - 1]))
strbuf_addstr(sb, "../");
strbuf_addstr(sb, in);
return sb->buf;
}
/*