From: Chih-Hung Hsieh <chh@google.com>
To: elfutils-devel@lists.fedorahosted.org
Subject: [PATCH] Do without on-stack variable length arrays.
Date: Fri, 04 Sep 2015 13:23:41 -0700 [thread overview]
Message-ID: <1441398221-19423-1-git-send-email-chh@google.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 13166 bytes --]
Prepare to compile without gnu99 extension.
Signed-off-by: Chih-Hung Hsieh <chh@google.com>
---
libdwfl/dwfl_module_getdwarf.c | 16 ++++++++--------
libdwfl/dwfl_segment_report_module.c | 16 ++++++++--------
libdwfl/elf-from-memory.c | 8 ++++----
libdwfl/link_map.c | 26 +++++++++++++-------------
libelf/elf_getarsym.c | 4 ++--
src/readelf.c | 27 +++++++++++++++------------
src/unstrip.c | 20 +++++++++++---------
7 files changed, 61 insertions(+), 56 deletions(-)
diff --git a/libdwfl/dwfl_module_getdwarf.c b/libdwfl/dwfl_module_getdwarf.c
index dba9d66..6d030f0 100644
--- a/libdwfl/dwfl_module_getdwarf.c
+++ b/libdwfl/dwfl_module_getdwarf.c
@@ -370,14 +370,14 @@ find_prelink_address_sync (Dwfl_Module *mod, struct dwfl_file *file)
{
typedef union
{
- Elf32_Phdr p32[phnum];
- Elf64_Phdr p64[phnum];
+ Elf32_Phdr p32[1]; /* phnum elements */
+ Elf64_Phdr p64[1]; /* phnum elements */
} phdr;
- phdr *phdrs = malloc (sizeof (phdr));
+ phdr *phdrs = malloc (sizeof (phdr) * phnum);
if (unlikely (phdrs == NULL))
return DWFL_E_NOMEM;
dst.d_buf = phdrs;
- dst.d_size = sizeof (phdr);
+ dst.d_size = sizeof (phdr) * phnum;
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
ehdr.e32.e_ident[EI_DATA]) == NULL))
{
@@ -414,14 +414,14 @@ find_prelink_address_sync (Dwfl_Module *mod, struct dwfl_file *file)
typedef union
{
- Elf32_Shdr s32[shnum - 1];
- Elf64_Shdr s64[shnum - 1];
+ Elf32_Shdr s32[1]; /* (shnum - 1) elements */
+ Elf64_Shdr s64[1]; /* (shnum - 1) elements */
} shdr;
- shdr *shdrs = malloc (sizeof (shdr));
+ shdr *shdrs = malloc (sizeof (shdr) * (shnum - 1));
if (unlikely (shdrs == NULL))
return DWFL_E_NOMEM;
dst.d_buf = shdrs;
- dst.d_size = sizeof (shdr);
+ dst.d_size = sizeof (shdr) * (shnum - 1);
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
ehdr.e32.e_ident[EI_DATA]) == NULL))
{
diff --git a/libdwfl/dwfl_segment_report_module.c b/libdwfl/dwfl_segment_report_module.c
index a0f07ad..8667538 100644
--- a/libdwfl/dwfl_segment_report_module.c
+++ b/libdwfl/dwfl_segment_report_module.c
@@ -406,17 +406,17 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
typedef union
{
- Elf32_Phdr p32[phnum];
- Elf64_Phdr p64[phnum];
+ Elf32_Phdr p32[1]; /* phnum elements */
+ Elf64_Phdr p64[1]; /* phnum elements */
} phdrsn;
- phdrsp = malloc (sizeof (phdrsn));
+ phdrsp = malloc (sizeof (phdrsn) * phnum);
if (unlikely (phdrsp == NULL))
return finish ();
phdrsn *phdrs = (phdrsn *) phdrsp;
xlateto.d_buf = phdrs;
- xlateto.d_size = sizeof (phdrsn);
+ xlateto.d_size = sizeof (phdrsn) * phnum;
/* Track the bounds of the file visible in memory. */
GElf_Off file_trimmed_end = 0; /* Proper p_vaddr + p_filesz end. */
@@ -757,10 +757,10 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
{
typedef union
{
- Elf32_Dyn d32[dyn_filesz / sizeof (Elf32_Dyn)];
- Elf64_Dyn d64[dyn_filesz / sizeof (Elf64_Dyn)];
+ Elf32_Dyn d32[1]; /* dyn_filesz / sizeof (Elf32_Dyn) */
+ Elf64_Dyn d64[1]; /* dyn_filesz / sizeof (Elf64_Dyn) */
} dynn;
- dyns = malloc (sizeof (dynn));
+ dyns = malloc (dyn_filesz);
if (unlikely (dyns == NULL))
return finish ();
dynn *dyn = (dynn *) dyns;
@@ -769,7 +769,7 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
xlatefrom.d_buf = (void *) dyn_data;
xlatefrom.d_size = dyn_filesz;
xlateto.d_buf = dyn;
- xlateto.d_size = sizeof (dynn);
+ xlateto.d_size = dyn_filesz;
if (ei_class == ELFCLASS32)
{
diff --git a/libdwfl/elf-from-memory.c b/libdwfl/elf-from-memory.c
index ed8f6e9..dc23845 100644
--- a/libdwfl/elf-from-memory.c
+++ b/libdwfl/elf-from-memory.c
@@ -193,11 +193,11 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
typedef union
{
- Elf32_Phdr p32[phnum];
- Elf64_Phdr p64[phnum];
+ Elf32_Phdr p32[1]; /* phnum elements */
+ Elf64_Phdr p64[1]; /* phnum elements */
} phdrsn;
- phdrsp = malloc (sizeof (phdrsn));
+ phdrsp = malloc (sizeof (phdrsn) * phnum);
if (unlikely (phdrsp == NULL))
{
free (buffer);
@@ -206,7 +206,7 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
phdrsn *phdrs = (phdrsn *) phdrsp;
xlateto.d_buf = phdrs;
- xlateto.d_size = sizeof (phdrsn);
+ xlateto.d_size = sizeof (phdrsn) * phnum;
/* Scan for PT_LOAD segments to find the total size of the file image. */
size_t contents_size = 0;
diff --git a/libdwfl/link_map.c b/libdwfl/link_map.c
index 030c600..b27c9f1 100644
--- a/libdwfl/link_map.c
+++ b/libdwfl/link_map.c
@@ -50,9 +50,9 @@ auxv_format_probe (const void *auxv, size_t size,
{
const union
{
- char buf[size];
- Elf32_auxv_t a32[size / sizeof (Elf32_auxv_t)];
- Elf64_auxv_t a64[size / sizeof (Elf64_auxv_t)];
+ char buf[1]; /* size bytes */
+ Elf32_auxv_t a32[1];
+ Elf64_auxv_t a64[1];
} *u = auxv;
inline bool check64 (size_t i)
@@ -282,8 +282,8 @@ report_r_debug (uint_fast8_t elfclass, uint_fast8_t elfdata,
const union
{
- Elf32_Addr a32[n];
- Elf64_Addr a64[n];
+ Elf32_Addr a32[1]; /* n elements */
+ Elf64_Addr a64[1]; /* n elements */
} *in = vaddr - read_vaddr + buffer;
if (elfclass == ELFCLASS32)
@@ -865,9 +865,9 @@ dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size,
{
Elf32_Phdr p32;
Elf64_Phdr p64;
- char data[phnum * phent];
+ char data[1]; /* (phnum * phent) bytes */
} data_buf;
- data_buf *buf = malloc (sizeof (data_buf));
+ data_buf *buf = malloc (phnum * phent);
if (unlikely (buf == NULL))
{
__libdwfl_seterrno (DWFL_E_NOMEM);
@@ -888,8 +888,8 @@ dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size,
/* We are looking for PT_DYNAMIC. */
const union
{
- Elf32_Phdr p32[phnum];
- Elf64_Phdr p64[phnum];
+ Elf32_Phdr p32[1]; /* phnum elements */
+ Elf64_Phdr p64[1]; /* phnum elements */
} *u = (void *) buf;
if (elfclass == ELFCLASS32)
{
@@ -959,9 +959,9 @@ dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size,
{
Elf32_Dyn d32;
Elf64_Dyn d64;
- char data[dyn_filesz];
+ char data[1]; /* dyn_filesz bytes */
} data_buf;
- data_buf *buf = malloc (sizeof (data_buf));
+ data_buf *buf = malloc (dyn_filesz);
if (unlikely (buf == NULL))
{
__libdwfl_seterrno (DWFL_E_NOMEM);
@@ -982,8 +982,8 @@ dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size,
/* We are looking for DT_DEBUG. */
const union
{
- Elf32_Dyn d32[dyn_filesz / sizeof (Elf32_Dyn)];
- Elf64_Dyn d64[dyn_filesz / sizeof (Elf64_Dyn)];
+ Elf32_Dyn d32[1]; /* dyn_filesz bytes */
+ Elf64_Dyn d64[1]; /* dyn_filesz bytes */
} *u = (void *) buf;
if (elfclass == ELFCLASS32)
{
diff --git a/libelf/elf_getarsym.c b/libelf/elf_getarsym.c
index 8324244..569477e 100644
--- a/libelf/elf_getarsym.c
+++ b/libelf/elf_getarsym.c
@@ -205,8 +205,8 @@ elf_getarsym (elf, ptr)
{
union
{
- uint32_t u32[n];
- uint64_t u64[n];
+ uint32_t u32[1]; /* n elements */
+ uint64_t u64[1]; /* n elements */
} *file_data;
char *str_data;
size_t sz = n * w;
diff --git a/src/readelf.c b/src/readelf.c
index d3c2b6b..ef66f0d 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -4943,7 +4943,7 @@ print_cfa_program (const unsigned char *readp, const unsigned char *const endp,
unsigned int version, unsigned int ptr_size,
Dwfl_Module *dwflmod, Ebl *ebl, Dwarf *dbg)
{
- char regnamebuf[REGNAMESZ];
+ char *regnamebuf = alloca (REGNAMESZ);
const char *regname (unsigned int regno)
{
register_info (ebl, regno, NULL, regnamebuf, NULL, NULL);
@@ -8378,11 +8378,13 @@ handle_core_item (Elf *core, const Ebl_Core_Item *item, const void *desc,
DO_TYPE (XWORD, Xword, "0x%.16" PRIx64, "%" PRId64); \
DO_TYPE (SXWORD, Sxword, "%" PRId64, "%" PRId64)
-#define DO_TYPE(NAME, Name, hex, dec) GElf_##Name Name[count]
- union { TYPES; } value;
+#define DO_TYPE(NAME, Name, hex, dec) GElf_##Name Name[2]
+ /* Name should have count elements and count >= 2 */
+ typedef union { TYPES; } value_t;
+ value_t *value = alloca (sizeof (value_t) / 2 * count);
#undef DO_TYPE
- void *data = &value;
+ void *data = value;
size_t size = gelf_fsize (core, item->type, count, EV_CURRENT);
size_t convsize = size;
if (repeated_size != NULL)
@@ -8413,7 +8415,7 @@ handle_core_item (Elf *core, const Ebl_Core_Item *item, const void *desc,
#define DO_TYPE(NAME, Name, hex, dec) \
case ELF_T_##NAME: \
colno = print_core_item (colno, ',', WRAP_COLUMN, \
- 0, item->name, dec, value.Name[0]); \
+ 0, item->name, dec, value->Name[0]); \
break
TYPES;
#undef DO_TYPE
@@ -8429,7 +8431,7 @@ handle_core_item (Elf *core, const Ebl_Core_Item *item, const void *desc,
#define DO_TYPE(NAME, Name, hex, dec) \
case ELF_T_##NAME: \
colno = print_core_item (colno, ',', WRAP_COLUMN, \
- 0, item->name, hex, value.Name[0]); \
+ 0, item->name, hex, value->Name[0]); \
break
TYPES;
#undef DO_TYPE
@@ -8511,8 +8513,8 @@ handle_core_item (Elf *core, const Ebl_Core_Item *item, const void *desc,
{
#define DO_TYPE(NAME, Name, hex, dec) \
case ELF_T_##NAME: \
- sec = value.Name[0]; \
- usec = value.Name[1]; \
+ sec = value->Name[0]; \
+ usec = value->Name[1]; \
break
TYPES;
#undef DO_TYPE
@@ -8542,12 +8544,12 @@ handle_core_item (Elf *core, const Ebl_Core_Item *item, const void *desc,
case 'c':
assert (count == 1);
colno = print_core_item (colno, ',', WRAP_COLUMN, 0, item->name,
- "%c", value.Byte[0]);
+ "%c", value->Byte[0]);
break;
case 's':
colno = print_core_item (colno, ',', WRAP_COLUMN, 0, item->name,
- "%.*s", (int) count, value.Byte);
+ "%.*s", (int) count, value->Byte);
break;
case '\n':
@@ -8891,8 +8893,9 @@ handle_core_registers (Ebl *ebl, Elf *core, const void *desc,
assert (maxnreg > 0);
}
- struct register_info regs[maxnreg];
- memset (regs, 0, sizeof regs);
+ const int sizeof_regs = sizeof (struct register_info) * maxnreg;
+ struct register_info *regs = alloca (sizeof_regs);
+ memset (regs, 0, sizeof_regs);
/* Sort to collect the sets together. */
int maxreg = 0;
diff --git a/src/unstrip.c b/src/unstrip.c
index 8833094..3f25201 100644
--- a/src/unstrip.c
+++ b/src/unstrip.c
@@ -1013,13 +1013,14 @@ find_alloc_sections_prelink (Elf *debug, Elf_Data *debug_shstrtab,
error (EXIT_FAILURE, 0, _("invalid contents in '%s' section"),
".gnu.prelink_undo");
- union
+ typedef union
{
- Elf32_Shdr s32[shnum - 1];
- Elf64_Shdr s64[shnum - 1];
- } shdr;
- dst.d_buf = &shdr;
- dst.d_size = sizeof shdr;
+ Elf32_Shdr s32[1]; /* (shnum - 1) elements */
+ Elf64_Shdr s64[1]; /* (shnum - 1) elements */
+ } shdr_t;
+ shdr_t *shdr = alloca (sizeof (shdr_t) * (shnum - 1));
+ dst.d_buf = shdr;
+ dst.d_size = sizeof (shdr_t) * (shnum - 1);
ELF_CHECK (gelf_xlatetom (main, &dst, &src,
main_ehdr->e_ident[EI_DATA]) != NULL,
_("cannot read '.gnu.prelink_undo' section: %s"));
@@ -1030,7 +1031,7 @@ find_alloc_sections_prelink (Elf *debug, Elf_Data *debug_shstrtab,
struct section *sec = &undo_sections[undo_nalloc];
if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32)
{
-#define COPY(field) sec->shdr.field = shdr.s32[i].field
+#define COPY(field) sec->shdr.field = shdr->s32[i].field
COPY (sh_name);
COPY (sh_type);
COPY (sh_flags);
@@ -1044,7 +1045,7 @@ find_alloc_sections_prelink (Elf *debug, Elf_Data *debug_shstrtab,
#undef COPY
}
else
- sec->shdr = shdr.s64[i];
+ sec->shdr = shdr->s64[i];
if (sec->shdr.sh_flags & SHF_ALLOC)
{
sec->shdr.sh_addr += bias;
@@ -1260,7 +1261,8 @@ copy_elided_sections (Elf *unstripped, Elf *stripped,
more sections in stripped file than debug file -- arguments reversed?"));
/* Cache the stripped file's section details. */
- struct section sections[stripped_shnum - 1];
+ struct section *sections =
+ alloca (sizeof (struct section) * (stripped_shnum - 1));
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (stripped, scn)) != NULL)
{
--
2.5.0.457.gab17608
next reply other threads:[~2015-09-04 20:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-04 20:23 Chih-Hung Hsieh [this message]
2015-09-04 20:51 Roland McGrath
2015-09-04 21:43 Chih-Hung Hsieh
2015-09-04 22:14 Roland McGrath
2015-09-08 21:10 Chih-Hung Hsieh
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