keep user-provided CFLAGS/LDFLAGS separate from those added by configure

[musl] / src / unistd / faccessat.c

diff --git a/src/unistd/faccessat.c b/src/unistd/faccessat.c
index 1efbb77..3347895 100644 (file)
--- a/src/unistd/faccessat.c
+++ b/src/unistd/faccessat.c
@@ -1,7 +1,63 @@
 #include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/wait.h>
 #include "syscall.h"
+#include "pthread_impl.h"
+
+struct ctx {
+       int fd;
+       const char *filename;
+       int amode;
+};
+
+static const int errors[] = {
+       0, -EACCES, -ELOOP, -ENAMETOOLONG, -ENOENT, -ENOTDIR,
+       -EROFS, -EBADF, -EINVAL, -ETXTBSY,
+       -EFAULT, -EIO, -ENOMEM,
+       -EBUSY
+};
+
+static int checker(void *p)
+{
+       struct ctx *c = p;
+       int ret;
+       int i;
+       if (__syscall(SYS_setregid, __syscall(SYS_getegid), -1)
+           || __syscall(SYS_setreuid, __syscall(SYS_geteuid), -1))
+               __syscall(SYS_exit, 1);
+       ret = __syscall(SYS_faccessat, c->fd, c->filename, c->amode, 0);
+       for (i=0; i < sizeof errors/sizeof *errors - 1 && ret!=errors[i]; i++);
+       return i;
+}
 
 int faccessat(int fd, const char *filename, int amode, int flag)
 {
-       return syscall(SYS_faccessat, fd, filename, amode, flag);
+       if (!flag || (flag==AT_EACCESS && getuid()==geteuid() && getgid()==getegid()))
+               return syscall(SYS_faccessat, fd, filename, amode, flag);
+
+       if (flag != AT_EACCESS)
+               return __syscall_ret(-EINVAL);
+
+       char stack[1024];
+       sigset_t set;
+       pid_t pid;
+       int ret = -EBUSY;
+       struct ctx c = { .fd = fd, .filename = filename, .amode = amode };
+
+       __block_all_sigs(&set);
+       
+       pid = __clone(checker, stack+sizeof stack, 0, &c);
+       if (pid > 0) {
+               int status;
+               do {
+                       __syscall(SYS_wait4, pid, &status, __WCLONE, 0);
+               } while (!WIFEXITED(status) && !WIFSIGNALED(status));
+               if (WIFEXITED(status))
+                       ret = errors[WEXITSTATUS(status)];
+       }
+
+       __restore_sigs(&set);
+
+       return __syscall_ret(ret);
 }