[libc] implement pathconf/fpathconf

libc/config/linux/aarch64/entrypoints.txt

@@ -283,6 +283,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup3
     libc.src.unistd.execve
     libc.src.unistd.fchdir
+    libc.src.unistd.fpathconf
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate
     libc.src.unistd.getcwd
@@ -294,6 +295,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.link
     libc.src.unistd.linkat
     libc.src.unistd.lseek
+    libc.src.unistd.pathconf
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read

libc/config/linux/riscv/entrypoints.txt

@@ -288,6 +288,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup3
     libc.src.unistd.execve
     libc.src.unistd.fchdir
+    libc.src.unistd.fpathconf
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate
     libc.src.unistd.getcwd
@@ -299,6 +300,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.link
     libc.src.unistd.linkat
     libc.src.unistd.lseek
+    libc.src.unistd.pathconf
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read

libc/config/linux/x86_64/entrypoints.txt

@@ -301,6 +301,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup3
     libc.src.unistd.execve
     libc.src.unistd.fchdir
+    libc.src.unistd.fpathconf
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate
     libc.src.unistd.getcwd
@@ -312,6 +313,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.link
     libc.src.unistd.linkat
     libc.src.unistd.lseek
+    libc.src.unistd.pathconf
     libc.src.unistd.pipe
     libc.src.unistd.pread
     libc.src.unistd.pwrite

libc/src/unistd/CMakeLists.txt

@@ -69,6 +69,13 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.fork
 )
 
+add_entrypoint_object(
+  fpathconf
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.fpathconf
+)
+
 add_entrypoint_object(
   execv
   ALIAS
@@ -160,6 +167,13 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.lseek
 )
 
+add_entrypoint_object(
+  pathconf
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.pathconf
+)
+
 add_entrypoint_object(
   pipe
   ALIAS

libc/src/unistd/fpathconf.h

@@ -0,0 +1,18 @@
+//===-- Implementation header for fpathconf ---------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_UNISTD_FSYNC_H
+#define LLVM_LIBC_SRC_UNISTD_FSYNC_H
+
+namespace LIBC_NAMESPACE {
+
+long fpathconf(int fd, int name);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_UNISTD_FSYNC_H

libc/src/unistd/linux/CMakeLists.txt

@@ -105,6 +105,19 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  fpathconf
+  SRCS
+    fpathconf.cpp
+  HDRS
+    ../fpathconf.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   execv
   SRCS
@@ -273,6 +286,19 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  pathconf
+  SRCS
+  pathconf.cpp
+  HDRS
+    ../pathconf.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   pipe
   SRCS

libc/src/unistd/linux/fpathconf.cpp

@@ -0,0 +1,118 @@
+//===-- Linux implementation of fpathconf ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include "src/errno/libc_errno.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE {
+
+static long filesizebits(const struct statfs &s) {
+  switch (s.f_type) {
+  case JFFS2_SUPER_MAGIC:
+  case MSDOS_SUPER_MAGIC:
+  case NCP_SUPER_MAGIC:
+    return 32;
+  }
+  return 64;
+}
+
+static long link_max(const struct statfs &s) {
+  switch (s.f_type) {
+  case EXT2_SUPER_MAGIC:
+    return 32000;
+  case MINIX_SUPER_MAGIC:
+    return 250;
+  case MINIX2_SUPER_MAGIC:
+    return 65530;
+  case REISERFS_SUPER_MAGIC:
+    return 0xffff - 1000;
+  case UFS_MAGIC:
+    return 32000;
+  }
+  return LINK_MAX;
+}
+
+static long _2_symlinks(const struct statfs &s) {
+  switch (s.f_type) {
+  case ADFS_SUPER_MAGIC:
+  case BFS_MAGIC:
+  case CRAMFS_MAGIC:
+  case EFS_SUPER_MAGIC:
+  case MSDOS_SUPER_MAGIC:
+  case QNX4_SUPER_MAGIC:
+    return 0;
+  }
+  return 1;
+}
+
+static long fpathconfig(const struct fstatfs &s, int name) {
+  switch (name) {
+  case _PC_LINK_MAX:
+    return link_max(s);
+
+  case _PC_FILESIZEBITS:
+    return filesizebits(s);
+
+  case _PC_2_SYMLINKS:
+    return _2_symlinks(s);
+
+  case _PC_REC_MIN_XFER_SIZE:
+    return s.f_bsize;
+
+  case _PC_ALLOC_SIZE_MIN:
+  case _PC_REC_XFER_ALIGN:
+    return s.f_frsize;
+
+  case _PC_MAX_CANON:
+    return _POSIX_MAX_CANON;
+
+  case _PC_MAX_INPUT:
+    return _POSIX_MAX_INPUT;
+
+  case _PC_NAME_MAX:
+    return s.f_namemax;
+
+  case _PC_PATH_MAX:
+    return _POSIX_PATH_MAX;
+
+  case _PC_PIPE_BUF:
+    return _POSIX_PIPE_BUF;
+
+  case _PC_CHOWN_RESTRICTED:
+    return _POSIX_CHOWN_RESTRICTED;
+
+  case _PC_NO_TRUNC:
+    return _POSIX_NO_TRUNC;
+
+  case _PC_VDISABLE:
+    return _POSIX_VDISABLE;
+
+  case _PC_ASYNC_IO:
+  case _PC_PRIO_IO:
+  case _PC_REC_INCR_XFER_SIZE:
+  case _PC_REC_MAX_XFER_SIZE:
+  case _PC_SYMLINK_MAX:
+  case _PC_SYNC_IO:
+  default:
+    return -1;
+  }
+}
+
+LLVM_LIBC_FUNCTION(long, fpathconf, (int fd, int name)) {
+  struct fstatfs sb;
+  cpp::optional<LinuxStatFs> result = linux_fstatfs(fd);
+  if (!result.has_value()) {
+    return -1;
+  }
+  return fpathconfig(sb, name);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/unistd/linux/pathconf.cpp

@@ -0,0 +1,121 @@
+//===-- Linux implementation of pathconf ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/unistd/pread.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+#include "src/__support/macros/sanitizer.h" // for MSAN_UNPOISON
+#include "src/errno/libc_errno.h"
+#include <stdint.h> // For uint64_t.
+#include <sys/fstatvfs.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE {
+
+static long filesizebits(const struct statfs &s) {
+  switch (s.f_type) {
+  case JFFS2_SUPER_MAGIC:
+  case MSDOS_SUPER_MAGIC:
+  case NCP_SUPER_MAGIC:
+    return 32;
+  }
+  return 64;
+}
+
+static long link_max(const struct statfs &s) {
+  switch (s.f_type) {
+  case EXT2_SUPER_MAGIC:
+    return 32000;
+  case MINIX_SUPER_MAGIC:
+    return 250;
+  case MINIX2_SUPER_MAGIC:
+    return 65530;
+  case REISERFS_SUPER_MAGIC:
+    return 0xffff - 1000;
+  case UFS_MAGIC:
+    return 32000;
+  }
+  return LINK_MAX;
+}
+
+static long _2_symlinks(const struct statfs &s) {
+  switch (s.f_type) {
+  case ADFS_SUPER_MAGIC:
+  case BFS_MAGIC:
+  case CRAMFS_MAGIC:
+  case EFS_SUPER_MAGIC:
+  case MSDOS_SUPER_MAGIC:
+  case QNX4_SUPER_MAGIC:
+    return 0;
+  }
+  return 1;
+}
+
+static long pathconfig(const struct statfs &s, int name) {
+  switch (name) {
+  case _PC_LINK_MAX:
+    return link_max(s);
+
+  case _PC_FILESIZEBITS:
+    return filesizebits(s);
+
+  case _PC_2_SYMLINKS:
+    return _2_symlinks(s);
+
+  case _PC_REC_MIN_XFER_SIZE:
+    return s.f_bsize;
+
+  case _PC_ALLOC_SIZE_MIN:
+  case _PC_REC_XFER_ALIGN:
+    return s.f_frsize;
+
+  case _PC_MAX_CANON:
+    return _POSIX_MAX_CANON;
+
+  case _PC_MAX_INPUT:
+    return _POSIX_MAX_INPUT;
+
+  case _PC_NAME_MAX:
+    return s.f_namemax;
+
+  case _PC_PATH_MAX:
+    return _POSIX_PATH_MAX;
+
+  case _PC_PIPE_BUF:
+    return _POSIX_PIPE_BUF;
+
+  case _PC_CHOWN_RESTRICTED:
+    return _POSIX_CHOWN_RESTRICTED;
+
+  case _PC_NO_TRUNC:
+    return _POSIX_NO_TRUNC;
+
+  case _PC_VDISABLE:
+    return _POSIX_VDISABLE;
+
+  case _PC_ASYNC_IO:
+  case _PC_PRIO_IO:
+  case _PC_REC_INCR_XFER_SIZE:
+  case _PC_REC_MAX_XFER_SIZE:
+  case _PC_SYMLINK_MAX:
+  case _PC_SYNC_IO:
+  default:
+    return -1;
+  }
+}
+
+LLVM_LIBC_FUNCTION(long, pathconf, (char *path, int name)) {
+  cpp::optional<LinuxStatFs> result = linux_statfs(const char *path);
+  if (!result.has_value()) {
+    return -1;
+  }
+  return pathconfig(result.value(), name);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/unistd/pathconf.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for pathconf ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_UNISTD_PREAD_H
+#define LLVM_LIBC_SRC_UNISTD_PREAD_H
+
+#include <unistd.h>
+
+namespace LIBC_NAMESPACE {
+
+long pathconf(char *path, int name);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_UNISTD_PREAD_H