From 0fbc34f028e9eb7705e1f4ee1591ecd6d05160e8 Mon Sep 17 00:00:00 2001 From: Daniel Palmer Date: Thu, 2 Jul 2026 17:50:59 +0900 Subject: tools/nolibc: unistd: Add getcwd() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add getcwd() for getting the current working directory. The behaviour matches what musl is doing except for one important difference: If the passed buf is NULL musl (and glibc) uses a big buffer on the stack and that is then strdup()'d and returned. According to the man page for getcwd() this is a glibc extension and I don't think we need it in nolibc. Signed-off-by: Daniel Palmer Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260702085101.3304547-2-daniel@thingy.jp Signed-off-by: Thomas Weißschuh --- tools/include/nolibc/unistd.h | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/tools/include/nolibc/unistd.h b/tools/include/nolibc/unistd.h index 79599ceef45d..2e0edbc26315 100644 --- a/tools/include/nolibc/unistd.h +++ b/tools/include/nolibc/unistd.h @@ -73,6 +73,48 @@ int ftruncate(int fd, off_t length) return __sysret(_sys_ftruncate(fd, length)); } +/* + * char *getcwd(char *buf, size_t size); + */ + +static __attribute__((unused)) +int _sys_getcwd(char *buf, size_t size) +{ + return __nolibc_syscall2(__NR_getcwd, buf, size); +} + +static __attribute__((unused)) +char *getcwd(char *buf, size_t size) +{ + int ret; + + /* Unlike other libc's we don't handle passing NULL for buf */ + if (!buf || !size) { + SET_ERRNO(EINVAL); + return NULL; + } + + ret = __sysret(_sys_getcwd(buf, size)); + + /* On error return NULL, __sysret() above will have set errno */ + if (ret < 0) + return NULL; + + /* Handle no path being written or the kernel putting + * "(unreachable)" into the buffer instead of a path. + * This matches what musl is doing. + */ + if (ret == 0 || buf[0] != '/') { + SET_ERRNO(ENOENT); + return NULL; + } + + /* ret must be the number of bytes written at this point, + * so return the pointer to buf. + */ + return buf; +} + static __attribute__((unused)) int msleep(unsigned int msecs) { -- cgit v1.2.3 From 94518b77e194d71b1d76a2dd75f4891954edc296 Mon Sep 17 00:00:00 2001 From: Daniel Palmer Date: Thu, 2 Jul 2026 17:51:00 +0900 Subject: tools/nolibc: unistd: Add readlink() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add readlink(). This is needed to test getcwd(). Signed-off-by: Daniel Palmer Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260702085101.3304547-3-daniel@thingy.jp Signed-off-by: Thomas Weißschuh --- tools/include/nolibc/unistd.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/tools/include/nolibc/unistd.h b/tools/include/nolibc/unistd.h index 2e0edbc26315..a264a20da13d 100644 --- a/tools/include/nolibc/unistd.h +++ b/tools/include/nolibc/unistd.h @@ -128,6 +128,22 @@ int msleep(unsigned int msecs) return 0; } +/* + * ssize_t readlink(const char *path, char *buf, size_t bufsiz); + */ + +static __attribute__((unused)) +ssize_t _sys_readlink(const char *path, char *buf, size_t bufsiz) +{ + return __nolibc_syscall4(__NR_readlinkat, AT_FDCWD, path, buf, bufsiz); +} + +static __attribute__((unused)) +ssize_t readlink(const char *path, char *buf, size_t bufsiz) +{ + return __sysret(_sys_readlink(path, buf, bufsiz)); +} + static __attribute__((unused)) unsigned int sleep(unsigned int seconds) { -- cgit v1.2.3 From 4f5777cfbd98c10e71c7fbfe4615dd499fada7b7 Mon Sep 17 00:00:00 2001 From: Daniel Palmer Date: Thu, 2 Jul 2026 17:51:01 +0900 Subject: selftests/nolibc: Add test for getcwd() and readlink() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a test that uses both getcwd() and readlink() so that both are exercised. First the happy path is tested by fetching what should be the same string via getcwd() and readlink() and checking they match. Then a few different combinations of bad parameters are passed to getcwd() to make sure it returns NULL and sets errno in those cases. Signed-off-by: Daniel Palmer Link: https://patch.msgid.link/20260702085101.3304547-4-daniel@thingy.jp Signed-off-by: Thomas Weißschuh --- tools/testing/selftests/nolibc/nolibc-test.c | 53 ++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index c1c1ce43a047..996e8d13508e 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -854,6 +854,58 @@ static int test_dirent(void) return 0; } +int test_getcwd(void) +{ + char cwd_syscall[PATH_MAX]; + char cwd_proc[PATH_MAX]; + ssize_t len; + + /* Read where the link /proc/self/cwd points */ + len = readlink("/proc/self/cwd", cwd_proc, sizeof(cwd_proc) - 1); + if (len <= 0) + return __LINE__; + + /* Terminate the string from readlink() */ + cwd_proc[len] = '\0'; + + /* Get the cwd via syscall */ + if (getcwd(cwd_syscall, sizeof(cwd_syscall)) == NULL) + return __LINE__; + + /* Fail if they aren't the same */ + if (strcmp(cwd_proc, cwd_syscall) != 0) + return __LINE__; + + /* Try getcwd() with NULL for the buffer, + * should return NULL and an error in errno. + * Other libc's allow this by allocating a buffer + * internally. + */ + if (is_nolibc) { + errno = 0; + if (getcwd(NULL, 0) != NULL || !errno) + return __LINE__; + } + + /* Try getcwd() with a buffer but make the size 0, + * should return NULL and an error in errno. + */ + errno = 0; + if (getcwd(cwd_syscall, 0) != NULL || !errno) + return __LINE__; + + /* Try getcwd() with a buffer but make the size 1, + * should return NULL and an error in errno because + * the string written to the buffer is terminated + * so you need at least 2 bytes even for "/". + */ + errno = 0; + if (getcwd(cwd_syscall, 1) != NULL || !errno) + return __LINE__; + + return 0; +} + int test_getrandom(void) { uint64_t rng = 0; @@ -1555,6 +1607,7 @@ int run_syscall(int min, int max) CASE_TEST(clock_getres); EXPECT_SYSZR(1, clock_getres(CLOCK_MONOTONIC, &ts)); break; CASE_TEST(clock_gettime); EXPECT_SYSZR(1, clock_gettime(CLOCK_MONOTONIC, &ts)); break; CASE_TEST(clock_settime); EXPECT_SYSER(1, clock_settime(CLOCK_MONOTONIC, &ts), -1, EINVAL); break; + CASE_TEST(getcwd); EXPECT_SYSZR(proc, test_getcwd()); break; CASE_TEST(getpid); EXPECT_SYSNE(1, getpid(), -1); break; CASE_TEST(getppid); EXPECT_SYSNE(1, getppid(), -1); break; CASE_TEST(gettid); EXPECT_SYSNE(has_gettid, gettid(), -1); break; -- cgit v1.2.3 From a3b2181459a2c74c03ddbad585f884eefc8ff8ff Mon Sep 17 00:00:00 2001 From: Thomas Weißschuh Date: Fri, 3 Jul 2026 19:30:16 +0200 Subject: tools/nolibc: mark arg1 operand in __nolibc_syscall0() as write-only MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit __nolibc_syscall0() does not set the arg1 variable before passing it to the asm block. This uninitialized variable read is undefined behavior. Clang can miscompile this. Mark the asm operand as write-only to fix this. Fixes: 8e1930296f92 ("tools/nolibc: Add support for SPARC") Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260703-nolibc-sparc-asm-v1-1-c7fe73e2e777@weissschuh.net --- tools/include/nolibc/arch-sparc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/include/nolibc/arch-sparc.h b/tools/include/nolibc/arch-sparc.h index ddae9bc10dfe..23fab40accfa 100644 --- a/tools/include/nolibc/arch-sparc.h +++ b/tools/include/nolibc/arch-sparc.h @@ -45,7 +45,7 @@ \ __asm__ volatile ( \ _NOLIBC_SYSCALL \ - : "+r"(_arg1) \ + : "=r"(_arg1) \ : "r"(_num) \ : "memory", "cc" \ ); \ -- cgit v1.2.3