libpkgconf: path: supply buffer to realpath #208

ariadne · 2021-01-08T10:04:15Z

grobian commented

2021-01-08 10:04:15 +00:00

(Migrated from github.com)

To avoid a crash on some platforms (like Darwin 9) provide a buffer to
realpath(3).

Darwin 9 (last PPC target) documents realpath needs to be given a buffer
to the resolved_path argument large enough to hold PATH_MAX bytes.
With NULL argument it crashes. Solaris makes no mention of
resolved_path to be allowed NULL, yet recent versions accept it and
malloc(3) accordingly.

Because the documentation explicitly mentions PATH_MAX being the limit
to what realpath(3) would write in resolved_path, switching to a static
buffer here doesn't limit resolution compared to dynamically allocating
a buffer by realpath(3).

While this change requires a bit more space on the stack, it avoids a
malloc/free sequence, and allows successful operation on (older)
platforms that lack support for dynamically allocating a return buffer
in realpath(3).

Signed-off-by: Fabian Groffen grobian@gentoo.org

To avoid a crash on some platforms (like Darwin 9) provide a buffer to realpath(3). Darwin 9 (last PPC target) documents realpath needs to be given a buffer to the resolved_path argument large enough to hold PATH_MAX bytes. With NULL argument it crashes. Solaris makes no mention of resolved_path to be allowed NULL, yet recent versions accept it and malloc(3) accordingly. Because the documentation explicitly mentions PATH_MAX being the limit to what realpath(3) would write in resolved_path, switching to a static buffer here doesn't limit resolution compared to dynamically allocating a buffer by realpath(3). While this change requires a bit more space on the stack, it avoids a malloc/free sequence, and allows successful operation on (older) platforms that lack support for dynamically allocating a return buffer in realpath(3). Signed-off-by: Fabian Groffen <grobian@gentoo.org>

ariadne commented

2021-01-08 23:45:36 +00:00

Note to self: change this PATH_MAX to our internal equivalent for HURD.

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