[PATCH] elf: Replace tst-p_alignmod1-editX with a python script

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

This avoid the cross-compiling breakage when the test should not run
($(run-built-tests) equal to no).

Checked on x86_64-linux-gnu and i686-linux-gnu as well with a cross
compile to aarch64-linux-gnu and powerpc64-linux-gnu.
---
 elf/Makefile               |  14 +--
 elf/tst-elf-edit.h         | 126 -----------------------
 elf/tst-p_alignmod1-edit.c |  27 -----
 elf/tst-p_alignmod2-edit.c |  27 -----
 scripts/tst-elf-edit.py    | 206 +++++++++++++++++++++++++++++++++++++
 5 files changed, 210 insertions(+), 190 deletions(-)
 delete mode 100644 elf/tst-elf-edit.h
 delete mode 100644 elf/tst-p_alignmod1-edit.c
 delete mode 100644 elf/tst-p_alignmod2-edit.c
 create mode 100644 scripts/tst-elf-edit.py

diff --git a/elf/Makefile b/elf/Makefile
index 41e0f2e8c4..daafb5cf12 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -413,8 +413,6 @@ tests += \
   tst-nodelete-opened \
   tst-noload \
   tst-null-argv \
-  tst-p_alignmod1-edit \
-  tst-p_alignmod2-edit \
   tst-p_align1 \
   tst-p_align2 \
   tst-p_align3 \
@@ -2607,23 +2605,19 @@ $(objpfx)tst-p_align1: $(objpfx)tst-p_alignmod1.so
 
 # Make a copy of tst-p_alignmod-base.so and lower p_align of the first
 # PT_LOAD segment.
-$(objpfx)tst-p_alignmod1.so: $(objpfx)tst-p_alignmod1-edit \
-			     $(objpfx)tst-p_alignmod-base.so
+$(objpfx)tst-p_alignmod1.so: $(objpfx)tst-p_alignmod-base.so
 	rm -f $@
 	cp $(objpfx)tst-p_alignmod-base.so $@
-	$(test-wrapper-env) $(run-program-env) $(rtld-prefix) \
-	  $(objpfx)tst-p_alignmod1-edit $@
+	$(PYTHON) $(..)scripts/tst-elf-edit.py -a half $@
 
 $(objpfx)tst-p_align2: $(objpfx)tst-p_alignmod2.so
 
 # Make a copy of tst-p_alignmod-base.so and update p_align of the first
 # PT_LOAD segment.
-$(objpfx)tst-p_alignmod2.so: $(objpfx)tst-p_alignmod2-edit \
-			     $(objpfx)tst-p_alignmod-base.so
+$(objpfx)tst-p_alignmod2.so: $(objpfx)tst-p_alignmod-base.so
 	rm -f $@
 	cp $(objpfx)tst-p_alignmod-base.so $@
-	$(test-wrapper-env) $(run-program-env) $(rtld-prefix) \
-	  $(objpfx)tst-p_alignmod2-edit $@
+	$(PYTHON) $(..)scripts/tst-elf-edit.py -a 1 $@
 
 LDFLAGS-tst-p_alignmod3.so += -Wl,-z,max-page-size=0x100,-z,common-page-size=0x100
 
diff --git a/elf/tst-elf-edit.h b/elf/tst-elf-edit.h
deleted file mode 100644
index b764e78933..0000000000
--- a/elf/tst-elf-edit.h
+++ /dev/null
@@ -1,126 +0,0 @@
-/* Update p_align of the first PT_LOAD segment.
-   Copyright (C) 2022 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <stdio.h>
-#include <stdbool.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <link.h>
-#include <error.h>
-#include <errno.h>
-#include <sys/stat.h>
-#include <sys/mman.h>
-
-const char *file_name;
-
-static size_t update_p_align (size_t);
-
-int
-main (int argc, char ** argv)
-{
-  if (argc != 2)
-    {
-      printf ("Usage: %s: file\n", argv[0]);
-      return 0;
-    }
-
-  file_name = argv[1];
-  struct stat statbuf;
-  int errno_saved;
-
-  if (stat (file_name, &statbuf) < 0)
-    error (1, errno, "%s: not exist", file_name);
-
-  ElfW(Ehdr) *ehdr;
-
-  if (statbuf.st_size < sizeof (*ehdr))
-    error (1, 0, "%s: too small", file_name);
-
-  int fd = open (file_name, O_RDWR);
-  if (fd < 0)
-    error (1, errno, "%s: can't open", file_name);
-
-  /* Map in the whole file.  */
-  void *base = mmap (NULL, statbuf.st_size, PROT_READ | PROT_WRITE,
-		     MAP_SHARED, fd, 0);
-  if (base == MAP_FAILED)
-    {
-      errno_saved = errno;
-      close (fd);
-      error (1, errno_saved, "%s: failed to map", file_name);
-    }
-
-  ehdr = (ElfW(Ehdr) *) base;
-  if (ehdr->e_ident[EI_MAG0] != ELFMAG0
-      || ehdr->e_ident[EI_MAG1] != ELFMAG1
-      || ehdr->e_ident[EI_MAG2] != ELFMAG2
-      || ehdr->e_ident[EI_MAG3] != ELFMAG3)
-    {
-      close (fd);
-      error (1, 0, "%s: bad ELF header", file_name);
-    }
-
-  if (ehdr->e_type != ET_DYN)
-    {
-      close (fd);
-      error (1, 0, "%s: not shared library", file_name);
-    }
-
-  bool unsupported_class = true;
-  switch (ehdr->e_ident[EI_CLASS])
-    {
-    default:
-      break;
-
-    case ELFCLASS32:
-      unsupported_class = __ELF_NATIVE_CLASS != 32;
-      break;
-
-    case ELFCLASS64:
-      unsupported_class = __ELF_NATIVE_CLASS != 64;
-      break;
-    }
-
-  if (unsupported_class)
-    {
-      close (fd);
-      error (1, 0, "%s: unsupported ELF class: %d",
-	     file_name, ehdr->e_ident[EI_CLASS]);
-    }
-
-  size_t phdr_size = sizeof (ElfW(Phdr)) * ehdr->e_phentsize;
-  if (statbuf.st_size < (ehdr->e_phoff + phdr_size))
-    {
-      close (fd);
-      error (1, 0, "%s: too small", file_name);
-    }
-
-  ElfW(Phdr) *phdr = (ElfW(Phdr) *) (base + ehdr->e_phoff);
-  for (int i = 0; i < ehdr->e_phnum; i++, phdr++)
-    if (phdr->p_type == PT_LOAD)
-      {
-	/* Update p_align of the first PT_LOAD segment.  */
-	phdr->p_align = update_p_align (phdr->p_align);
-	break;
-      }
-
-  munmap (base, statbuf.st_size);
-  close (fd);
-
-  return 0;
-}
diff --git a/elf/tst-p_alignmod1-edit.c b/elf/tst-p_alignmod1-edit.c
deleted file mode 100644
index 06d9c636fd..0000000000
--- a/elf/tst-p_alignmod1-edit.c
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Reduce p_align of the first PT_LOAD segment by half.
-   Copyright (C) 2022 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include "tst-elf-edit.h"
-
-/* Reduce p_align by half.  */
-
-static size_t
-update_p_align (size_t p_align)
-{
-  return p_align >> 1;
-}
diff --git a/elf/tst-p_alignmod2-edit.c b/elf/tst-p_alignmod2-edit.c
deleted file mode 100644
index 4c2ae65b4e..0000000000
--- a/elf/tst-p_alignmod2-edit.c
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Set p_align of the first PT_LOAD segment to 1.
-   Copyright (C) 2022 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include "tst-elf-edit.h"
-
-/* Set p_align to 1.  */
-
-static size_t
-update_p_align (size_t p_align __attribute__ ((unused)))
-{
-  return 1;
-}
diff --git a/scripts/tst-elf-edit.py b/scripts/tst-elf-edit.py
new file mode 100644
index 0000000000..1fb9b8e0fe
--- /dev/null
+++ b/scripts/tst-elf-edit.py
@@ -0,0 +1,206 @@
+#!/usr/bin/python3
+# ELF editor for load align tests.
+# Copyright (C) 2022 Free Software Foundation, Inc.
+# Copyright The GNU Toolchain Authors.
+# This file is part of the GNU C Library.
+#
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <https://www.gnu.org/licenses/>.
+
+import argparse
+import os
+import sys
+import struct
+
+EI_NIDENT=16
+
+EI_MAG0=0
+ELFMAG0=b'\x7f'
+EI_MAG1=1
+ELFMAG1=b'E'
+EI_MAG2=2
+ELFMAG2=b'L'
+EI_MAG3=3
+ELFMAG3=b'F'
+
+EI_CLASS=4
+ELFCLASSNONE=b'0'
+ELFCLASS32=b'\x01'
+ELFCLASS64=b'\x02'
+
+EI_DATA=5
+ELFDATA2LSB=b'\x01'
+ELFDATA2MSB=b'\x02'
+
+ET_DYN=3
+
+PT_LOAD=1
+
+def elf_types_fmts(e_ident):
+    endian = '<' if e_ident[EI_DATA] == ELFDATA2LSB else '>'
+    addr = 'I' if e_ident[EI_CLASS] == ELFCLASS32 else 'Q'
+    off = 'I' if e_ident[EI_CLASS] == ELFCLASS32 else 'Q'
+    return (endian, addr, off)
+
+class Elf_Ehdr:
+    def __init__(self, e_ident):
+        endian, addr, off = elf_types_fmts(e_ident)
+        self.fmt = '{0}HHI{1}{2}{2}IHHHHHH'.format(endian, addr, off)
+        self.len = struct.calcsize(self.fmt)
+
+    def read(self, f):
+        buf = f.read(self.len)
+        if not buf:
+            error('{}: header too small'.format(f.name))
+        data = struct.unpack(self.fmt, buf)
+        self.e_type = data[0]
+        self.e_machine = data[1]
+        self.e_version = data[2]
+        self.e_entry = data[3]
+        self.e_phoff = data[4]
+        self.e_shoff = data[5]
+        self.e_flags = data[6]
+        self.e_ehsize = data[7]
+        self.e_phentsize= data[8]
+        self.e_phnum = data[9]
+        self.e_shstrndx = data[10]
+
+
+class Elf_Phdr:
+    def __init__(self, e_ident):
+        endian, addr, off = elf_types_fmts(e_ident)
+        self.ei_class = e_ident[EI_CLASS]
+        if self.ei_class == ELFCLASS32:
+            self.fmt = '{0}I{2}{1}{1}IIII'.format(endian, addr, off)
+        else:
+            self.fmt = '{0}II{2}{1}{1}QQQ'.format(endian, addr, off)
+        self.len = struct.calcsize(self.fmt)
+
+    def read(self, f):
+        buf = f.read(self.len)
+        if not buf:
+            error('{}: program header too small'.format(f.name))
+        data = struct.unpack(self.fmt, buf)
+        if self.ei_class == ELFCLASS32:
+            self.p_type = data[0]
+            self.p_offset = data[1]
+            self.p_vaddr = data[2]
+            self.p_paddr = data[3]
+            self.p_filesz = data[4]
+            self.p_memsz = data[5]
+            self.p_flags = data[6]
+            self.p_align = data[7]
+        else:
+            self.p_type = data[0]
+            self.p_flags = data[1]
+            self.p_offset = data[2]
+            self.p_vaddr = data[3]
+            self.p_paddr = data[4]
+            self.p_filesz = data[5]
+            self.p_memsz = data[6]
+            self.p_align = data[7]
+
+    def write(self, f):
+        if self.ei_class == ELFCLASS32:
+            data = struct.pack(self.fmt,
+                               self.p_type,
+                               self.p_offset,
+                               self.p_vaddr,
+                               self.p_paddr,
+                               self.p_filesz,
+                               self.p_memsz,
+                               self.p_flags,
+                               self.p_align)
+        else:
+            data = struct.pack(self.fmt,
+                               self.p_type,
+                               self.p_flags,
+                               self.p_offset,
+                               self.p_vaddr,
+                               self.p_paddr,
+                               self.p_filesz,
+                               self.p_memsz,
+                               self.p_align)
+        f.write(data)
+
+
+def error(msg):
+    print(msg, file=sys.stderr)
+    sys.exit(1)
+
+
+def elf_edit_align(phdr, align):
+    if align == 'half':
+        phdr.p_align = phdr.p_align >> 1
+    else:
+        phdr.p_align = int(align)
+
+
+def elf_edit(f, align):
+    ei_nident_fmt = 'c' * EI_NIDENT
+    ei_nident_len = struct.calcsize(ei_nident_fmt)
+
+    data = f.read(ei_nident_len)
+    if not data:
+      error('{}: e_nident too small'.format(f.name))
+    e_ident = struct.unpack(ei_nident_fmt, data)
+
+    if e_ident[EI_MAG0] != ELFMAG0 \
+       or e_ident[EI_MAG1] != ELFMAG1 \
+       or e_ident[EI_MAG2] != ELFMAG2 \
+       or e_ident[EI_MAG3] != ELFMAG3:
+      error('{}: bad ELF header'.format(f.name))
+
+    if e_ident[EI_CLASS] != ELFCLASS32 \
+       and e_ident[EI_CLASS] != ELFCLASS64:
+      error('{}: unsupported ELF class: {}'.format(f.name, e_ident[EI_CLASS]))
+
+    if e_ident[EI_DATA] != ELFDATA2LSB \
+       and e_ident[EI_DATA] != ELFDATA2MSB: \
+      error('{}: unsupported ELF data: {}'.format(f.name, e_ident[EI_DATA]))
+
+    ehdr = Elf_Ehdr(e_ident)
+    ehdr.read(f)
+    if ehdr.e_type != ET_DYN:
+       error('{}: not a shared library'.format(f.name))
+
+    phdr = Elf_Phdr(e_ident)
+    for i in range(0, ehdr.e_phnum):
+        f.seek(ehdr.e_phoff + i * phdr.len)
+        phdr.read(f)
+        if phdr.p_type == PT_LOAD:
+            elf_edit_align(phdr, align)
+            f.seek(ehdr.e_phoff + i * phdr.len)
+            phdr.write(f)
+            break
+
+
+def get_parser():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('-a', dest='align', required=True,
+                        help='How to set the LOAD alignment')
+    parser.add_argument('output',
+                        help='ELF file to edit')
+    return parser
+
+
+def main(argv):
+    parser = get_parser()
+    opts = parser.parse_args(argv)
+    with open(opts.output, 'r+b') as fout:
+       elf_edit(fout, opts.align)
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])
-- 
2.32.0