klibc-bot for Ben Hutchings
2016-Jan-06 01:54 UTC
[klibc] [klibc:master] Implement realpath()
Commit-ID: 32b36eb98fafad924f3f69904d74d2f2168a4753 Gitweb: http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=32b36eb98fafad924f3f69904d74d2f2168a4753 Author: Ben Hutchings <ben at decadent.org.uk> AuthorDate: Wed, 6 Jan 2016 01:08:47 +0000 Committer: H. Peter Anvin <hpa at linux.intel.com> CommitDate: Tue, 5 Jan 2016 17:48:43 -0800 [klibc] Implement realpath() This is needed as the basis for the readlink -f option. Signed-off-by: Ben Hutchings <ben at decadent.org.uk> Signed-off-by: H. Peter Anvin <hpa at linux.intel.com> --- usr/include/stdlib.h | 2 ++ usr/klibc/Kbuild | 2 +- usr/klibc/realpath.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 52 insertions(+), 1 deletion(-) diff --git a/usr/include/stdlib.h b/usr/include/stdlib.h index 406f446..856c647 100644 --- a/usr/include/stdlib.h +++ b/usr/include/stdlib.h @@ -92,4 +92,6 @@ static __inline__ int grantpt(int __fd) return 0; /* devpts does this all for us! */ } +__extern char *realpath(const char *, char *); + #endif /* _STDLIB_H */ diff --git a/usr/klibc/Kbuild b/usr/klibc/Kbuild index d3e2b9f..7d95e87 100644 --- a/usr/klibc/Kbuild +++ b/usr/klibc/Kbuild @@ -61,7 +61,7 @@ klib-y += vsnprintf.o snprintf.o vsprintf.o sprintf.o \ send.o recv.o \ access.o chmod.o chown.o dup2.o mknod.o poll.o rename.o stat.o \ lchown.o link.o rmdir.o unlink.o utimes.o lstat.o mkdir.o \ - readlink.o select.o symlink.o pipe.o \ + readlink.o realpath.o select.o symlink.o pipe.o \ ctype/isalnum.o ctype/isalpha.o ctype/isascii.o \ ctype/isblank.o ctype/iscntrl.o ctype/isdigit.o \ ctype/isgraph.o ctype/islower.o ctype/isprint.o \ diff --git a/usr/klibc/realpath.c b/usr/klibc/realpath.c new file mode 100644 index 0000000..1474b1e --- /dev/null +++ b/usr/klibc/realpath.c @@ -0,0 +1,49 @@ +#include <fcntl.h> +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <sys/types.h> +#include <unistd.h> + +/* + * Note that this requires name to refer to an existing file. This is + * correct according to POSIX. However, BSD and GNU implementations + * also allow name to refer to a non-existing file in an existing + * directory. + */ + +char *realpath(const char *name, char *resolved_name) +{ + static const char proc_fd_prefix[] = "/proc/self/fd/"; + char proc_fd_name[sizeof(proc_fd_prefix) + sizeof(int) * 3]; + int allocated = 0; + int fd; + ssize_t len; + + /* Open for path lookup only */ + fd = open(name, O_PATH); + if (fd < 0) + return NULL; + + if (!resolved_name) { + resolved_name = malloc(PATH_MAX); + if (!resolved_name) + goto out_close; + allocated = 1; + } + + /* Use procfs to read back the resolved name */ + sprintf(proc_fd_name, "%s%d", proc_fd_prefix, fd); + len = readlink(proc_fd_name, resolved_name, PATH_MAX - 1); + if (len < 0) { + if (allocated) + free(resolved_name); + resolved_name = NULL; + } else { + resolved_name[len] = 0; + } + +out_close: + close(fd); + return resolved_name; +}