diff mbox series

[v2,03/16] Use configure to detect HAVE_DECL_MMAP and use it for system doesn't provide sys/mman.h

Message ID 20221217165213.152-4-luoyonggang@gmail.com
State Rejected
Headers
Series Patches for building with mingw/gcc msvc/clang-cl |

Commit Message

Yonggang Luo Dec. 17, 2022, 4:52 p.m. UTC 
  Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
---
 configure.ac              | 1 +
 lib/crc32_file.c          | 4 ++--
 lib/system.h              | 2 ++
 libelf/elf32_updatefile.c | 3 ++-
 libelf/elf_begin.c        | 5 ++++-
 libelf/elf_end.c          | 2 ++
 libelf/elf_update.c       | 5 ++++-
 7 files changed, 17 insertions(+), 5 deletions(-)

Comments

Mark Wielaard Feb. 23, 2023, 10:52 a.m. UTC | #1 
Hi,

See also the discussion on v1 of this patch:
https://inbox.sourceware.org/elfutils-devel/f352dba78caee57afc17995f8e36d28ae98afbc0.camel@klomp.org/#r

I think we need to think about what the libelf API looks like without
mmap. In particular I think we need to decide what to do with the
Elf_Cmds:

  ELF_C_READ_MMAP,              /* Read, but mmap the file if possible.  */
  ELF_C_RDWR_MMAP,              /* Read and write, with mmap.  */
  ELF_C_WRITE_MMAP,             /* Write, with mmap.  */
  ELF_C_READ_MMAP_PRIVATE,      /* Read, but memory is writable, results are
                                   not written to the file.  */

Specifically because libdw does reply on some of them.

Thanks,

Mark
diff mbox series

Patch

diff --git a/configure.ac b/configure.ac
index 59be27ac..b84623fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -428,6 +428,7 @@  AC_CHECK_DECLS([memrchr, rawmemchr],[],[],
                [#define _GNU_SOURCE
                 #include <string.h>])
 AC_CHECK_DECLS([powerof2],[],[],[#include <sys/param.h>])
+AC_CHECK_DECLS([mmap],[],[],[#include <sys/mman.h>])
 AC_CHECK_DECLS([mempcpy],[],[],
                [#define _GNU_SOURCE
                 #include <string.h>])
diff --git a/lib/crc32_file.c b/lib/crc32_file.c
index f7607d0b..66833702 100644
--- a/lib/crc32_file.c
+++ b/lib/crc32_file.c
@@ -32,9 +32,7 @@ 
 
 #include "libeu.h"
 #include <errno.h>
-#include <unistd.h>
 #include <sys/stat.h>
-#include <sys/mman.h>
 #include "system.h"
 
 int
@@ -45,6 +43,7 @@  crc32_file (int fd, uint32_t *resp)
   off_t off = 0;
   ssize_t count;
 
+#if HAVE_DECL_MMAP
   struct stat st;
   if (fstat (fd, &st) == 0)
     {
@@ -78,6 +77,7 @@  crc32_file (int fd, uint32_t *resp)
 	  munmap (mapped, mapsize);
 	}
     }
+#endif
 
   while ((count = TEMP_FAILURE_RETRY (pread (fd, buffer, sizeof buffer,
 					     off))) > 0)
diff --git a/lib/system.h b/lib/system.h
index bbbe06c4..561d3e03 100644
--- a/lib/system.h
+++ b/lib/system.h
@@ -42,7 +42,9 @@ 
 /* System dependend headers */
 #include <byteswap.h>
 #include <endian.h>
+#if HAVE_DECL_MMAP
 #include <sys/mman.h>
+#endif
 #include <sys/param.h>
 #include <unistd.h>
 
diff --git a/libelf/elf32_updatefile.c b/libelf/elf32_updatefile.c
index 46afa1f4..8229fd26 100644
--- a/libelf/elf32_updatefile.c
+++ b/libelf/elf32_updatefile.c
@@ -96,7 +96,7 @@  sort_sections (Elf_Scn **scns, Elf_ScnList *list)
   qsort (scns, scnp - scns, sizeof (*scns), compare_sections);
 }
 
-
+#if HAVE_DECL_MMAP
 static inline void
 fill_mmap (size_t offset, char *last_position, char *scn_start,
            char *const shdr_start, char *const shdr_end)
@@ -482,6 +482,7 @@  __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
 
   return 0;
 }
+#endif
 
 
 /* Size of the buffer we use to generate the blocks of fill bytes.  */
diff --git a/libelf/elf_begin.c b/libelf/elf_begin.c
index fe8c640a..6d31882e 100644
--- a/libelf/elf_begin.c
+++ b/libelf/elf_begin.c
@@ -645,10 +645,12 @@  static struct Elf *
 read_file (int fildes, int64_t offset, size_t maxsize,
 	   Elf_Cmd cmd, Elf *parent)
 {
+#if HAVE_DECL_MMAP
   void *map_address = NULL;
   int use_mmap = (cmd == ELF_C_READ_MMAP || cmd == ELF_C_RDWR_MMAP
 		  || cmd == ELF_C_WRITE_MMAP
 		  || cmd == ELF_C_READ_MMAP_PRIVATE);
+#endif
 
   if (parent == NULL)
     {
@@ -669,7 +671,7 @@  read_file (int fildes, int64_t offset, size_t maxsize,
       /* The parent is already loaded.  Use it.  */
       assert (maxsize != ~((size_t) 0));
     }
-
+#if HAVE_DECL_MMAP
   if (use_mmap)
     {
       if (parent == NULL)
@@ -713,6 +715,7 @@  read_file (int fildes, int64_t offset, size_t maxsize,
 
       return result;
     }
+#endif
 
   /* Otherwise we have to do it the hard way.  We read as much as necessary
      from the file whenever we need information which is not available.  */
diff --git a/libelf/elf_end.c b/libelf/elf_end.c
index 5c451f36..8023b216 100644
--- a/libelf/elf_end.c
+++ b/libelf/elf_end.c
@@ -222,8 +222,10 @@  elf_end (Elf *elf)
       /* The file was read or mapped for this descriptor.  */
       if ((elf->flags & ELF_F_MALLOCED) != 0)
 	free (elf->map_address);
+#if HAVE_DECL_MMAP
       else if ((elf->flags & ELF_F_MMAPPED) != 0)
 	munmap (elf->map_address, elf->maximum_size);
+#endif
     }
 
   rwlock_unlock (elf->lock);
diff --git a/libelf/elf_update.c b/libelf/elf_update.c
index 56af3a1c..e81eb6c9 100644
--- a/libelf/elf_update.c
+++ b/libelf/elf_update.c
@@ -64,7 +64,7 @@  write_file (Elf *elf, int64_t size, int change_bo, size_t shnum)
       __libelf_seterrno (ELF_E_WRITE_ERROR);
       return -1;
     }
-
+#if HAVE_DECL_MMAP
   /* Try to map the file if this isn't done yet.  */
   if (elf->map_address == NULL && elf->cmd == ELF_C_WRITE_MMAP)
     {
@@ -125,6 +125,7 @@  write_file (Elf *elf, int64_t size, int change_bo, size_t shnum)
 	size = -1;
     }
   else
+#endif
     {
       /* The file is not mmaped.  */
       if ((class == ELFCLASS32
@@ -145,6 +146,7 @@  write_file (Elf *elf, int64_t size, int change_bo, size_t shnum)
       size = -1;
     }
 
+#if HAVE_DECL_MMAP
   /* POSIX says that ftruncate and write may clear the S_ISUID and S_ISGID
      mode bits.  So make sure we restore them afterwards if they were set.
      This is not atomic if someone else chmod's the file while we operate.  */
@@ -156,6 +158,7 @@  write_file (Elf *elf, int64_t size, int change_bo, size_t shnum)
       __libelf_seterrno (ELF_E_WRITE_ERROR);
       size = -1;
     }
+#endif
 
   if (size != -1 && elf->parent == NULL)
     elf->maximum_size = size;