[RFC] new helper funcs for alloca/malloc with mmu/nommu
Carmelo AMOROSO
carmelo.amoroso at st.com
Tue Jul 27 06:02:07 UTC 2010
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On 7/27/2010 7:57 AM, Mike Frysinger wrote:
> The rpc rcmd code has some ugly ifdef mazes to handle mmu/nommu differences
> just to select alloca or malloc. Unify those with some helper macros in a
> new header, and then convert the rcmd code over to it.
>
> This is all geared towards fixing the getdents helper functions which only
> use alloca() atm. Now that we have helper functions, convert the getdents
> functions over too.
>
> Signed-off-by: Mike Frysinger <vapier at gentoo.org>
> ---
> libc/inet/rpc/rcmd.c | 60 ++++++-------------------
> libc/stdlib/malloc-standard/malloc.h | 11 ++---
> libc/sysdeps/linux/common/bits/uClibc_alloc.h | 23 +++++++++
> libc/sysdeps/linux/common/getdents.c | 10 +++-
> libc/sysdeps/linux/common/getdents64.c | 10 +++-
> 5 files changed, 55 insertions(+), 59 deletions(-)
> create mode 100644 libc/sysdeps/linux/common/bits/uClibc_alloc.h
>
> diff --git a/libc/inet/rpc/rcmd.c b/libc/inet/rpc/rcmd.c
> index 628c291..fb1bd93 100644
> --- a/libc/inet/rpc/rcmd.c
> +++ b/libc/inet/rpc/rcmd.c
> @@ -69,7 +69,6 @@ static char sccsid[] = "@(#)rcmd.c 8.3 (Berkeley) 3/26/94";
> #include <netinet/in.h>
> #include <arpa/inet.h>
>
> -#include <alloca.h>
> #include <signal.h>
> #include <fcntl.h>
> #include <netdb.h>
> @@ -86,6 +85,7 @@ static char sccsid[] = "@(#)rcmd.c 8.3 (Berkeley) 3/26/94";
> #include <wchar.h>
> #endif
> #include <sys/uio.h>
> +#include <bits/uClibc_alloc.h>
>
>
> /* some forward declarations */
> @@ -116,11 +116,7 @@ int rcmd(char **ahost, u_short rport, const char *locuser, const char *remuser,
>
> #ifdef __UCLIBC_HAS_REENTRANT_RPC__
> hstbuflen = 1024;
> -#ifdef __ARCH_USE_MMU__
> - tmphstbuf = alloca (hstbuflen);
> -#else
> - tmphstbuf = malloc (hstbuflen);
> -#endif
> + tmphstbuf = stack_heap_alloc(hstbuflen);
>
> while (gethostbyname_r (*ahost, &hostbuf, tmphstbuf,
> hstbuflen, &hp, &herr) != 0 || hp == NULL)
> @@ -128,9 +124,7 @@ int rcmd(char **ahost, u_short rport, const char *locuser, const char *remuser,
> if (herr != NETDB_INTERNAL || errno != ERANGE)
> {
> __set_h_errno (herr);
> -#ifndef __ARCH_USE_MMU__
> - free(tmphstbuf);
> -#endif
> + stack_heap_free(tmphstbuf);
> herror(*ahost);
> return -1;
> }
> @@ -138,17 +132,11 @@ int rcmd(char **ahost, u_short rport, const char *locuser, const char *remuser,
> {
> /* Enlarge the buffer. */
> hstbuflen *= 2;
> -#ifdef __ARCH_USE_MMU__
> - tmphstbuf = alloca (hstbuflen);
> -#else
> - free(tmphstbuf);
> - tmphstbuf = malloc (hstbuflen);
> -#endif
> + stack_heap_free(tmphstbuf);
> + tmphstbuf = stack_heap_alloc(hstbuflen);
> }
> }
> -#ifndef __ARCH_USE_MMU__
> - free(tmphstbuf);
> -#endif
> + stack_heap_free(tmphstbuf);
> #else /* call the non-reentrant version */
> if ((hp = gethostbyname(*ahost)) == NULL) {
> return -1;
> @@ -331,35 +319,23 @@ int ruserok(const char *rhost, int superuser, const char *ruser,
>
> #ifdef __UCLIBC_HAS_REENTRANT_RPC__
> buflen = 1024;
> -#ifdef __ARCH_USE_MMU__
> - buffer = alloca (buflen);
> -#else
> - buffer = malloc (buflen);
> -#endif
> + buffer = stack_heap_alloc(buflen);
>
> while (gethostbyname_r (rhost, &hostbuf, buffer,
> buflen, &hp, &herr) != 0 || hp == NULL)
> {
> if (herr != NETDB_INTERNAL || errno != ERANGE) {
> -#ifndef __ARCH_USE_MMU__
> - free(buffer);
> -#endif
> + stack_heap_free(buffer);
> return -1;
> } else
> {
> /* Enlarge the buffer. */
> buflen *= 2;
> -#ifdef __ARCH_USE_MMU__
> - buffer = alloca (buflen);
> -#else
> - free(buffer);
> - buffer = malloc (buflen);
> -#endif
> + stack_heap_free(buffer);
> + buffer = stack_heap_alloc(buflen);
> }
> }
> -#ifndef __ARCH_USE_MMU__
> - free(buffer);
> -#endif
> + stack_heap_free(buffer);
> #else
> if ((hp = gethostbyname(rhost)) == NULL) {
> return -1;
> @@ -452,23 +428,15 @@ iruserok2 (u_int32_t raddr, int superuser, const char *ruser, const char *luser,
> #ifdef __UCLIBC_HAS_REENTRANT_RPC__
> size_t buflen = sysconf (_SC_GETPW_R_SIZE_MAX);
> struct passwd pwdbuf;
> -#ifdef __ARCH_USE_MMU__
> - char *buffer = alloca (buflen);
> -#else
> - char *buffer = malloc (buflen);
> -#endif
> + char *buffer = stack_heap_alloc(buflen);
>
> if (getpwnam_r (luser, &pwdbuf, buffer,
> buflen, &pwd) != 0 || pwd == NULL)
> {
> -#ifndef __ARCH_USE_MMU__
> - free(buffer);
> -#endif
> + stack_heap_free(buffer);
> return -1;
> }
> -#ifndef __ARCH_USE_MMU__
> - free(buffer);
> -#endif
> + stack_heap_free(buffer);
> #else
> if ((pwd = getpwnam(luser)) == NULL)
> return -1;
> diff --git a/libc/stdlib/malloc-standard/malloc.h b/libc/stdlib/malloc-standard/malloc.h
> index 7a2e66d..73d4b12 100644
> --- a/libc/stdlib/malloc-standard/malloc.h
> +++ b/libc/stdlib/malloc-standard/malloc.h
> @@ -349,16 +349,13 @@ __UCLIBC_MUTEX_EXTERN(__malloc_lock);
> #endif
>
> #ifdef __ARCH_USE_MMU__
> -
> -#define MMAP(addr, size, prot) \
> - (mmap((addr), (size), (prot), MAP_PRIVATE|MAP_ANONYMOUS, 0, 0))
> -
> +# define _MAP_UNINITIALIZE 0
> #else
> +# define _MAP_UNINITIALIZE MAP_UNINITIALIZE
> +#endif
>
> #define MMAP(addr, size, prot) \
> - (mmap((addr), (size), (prot), MAP_SHARED|MAP_ANONYMOUS|MAP_UNINITIALIZE, 0, 0))
> -
> -#endif
> + (mmap((addr), (size), (prot), MAP_PRIVATE|MAP_ANONYMOUS|_MAP_UNINITIALIZE, 0, 0))
>
>
> /* ----------------------- Chunk representations ----------------------- */
> diff --git a/libc/sysdeps/linux/common/bits/uClibc_alloc.h b/libc/sysdeps/linux/common/bits/uClibc_alloc.h
> new file mode 100644
> index 0000000..0f13787
> --- /dev/null
> +++ b/libc/sysdeps/linux/common/bits/uClibc_alloc.h
> @@ -0,0 +1,23 @@
> +/*
> + * Macros to transparently switch between the stack and heap for large
> + * allocations. The former is useful on MMU systems as it results in
> + * smaller code, but the latter is required on NoMMU systems. This is
> + * due to small stacks that cannot grow and so doing large allocs will
> + * cause a stack overflow.
> + */
> +
> +#ifndef _UCLIBC_ALLOC_H
> +#define _UCLIBC_ALLOC_H
> +
> +#include <alloca.h>
> +#include <stdlib.h>
> +
> +#ifdef __ARCH_USE_MMU__
> +# define stack_heap_alloc(x) alloca(x)
> +# define stack_heap_free(x) do { if (0) free(x); } while (0)
> +#else
> +# define stack_heap_alloc(x) malloc(x)
> +# define stack_heap_free(x) free(x)
> +#endif
> +
> +#endif
> diff --git a/libc/sysdeps/linux/common/getdents.c b/libc/sysdeps/linux/common/getdents.c
> index 5dda190..46f7b8e 100644
> --- a/libc/sysdeps/linux/common/getdents.c
> +++ b/libc/sysdeps/linux/common/getdents.c
> @@ -4,7 +4,6 @@
> * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
> */
>
> -#include <alloca.h>
> #include <assert.h>
> #include <errno.h>
> #include <dirent.h>
> @@ -17,6 +16,7 @@
> #include <sys/syscall.h>
> #include <bits/kernel_types.h>
> #include <bits/kernel-features.h>
> +#include <bits/uClibc_alloc.h>
>
> #if !(defined __UCLIBC_HAS_LFS__ && defined __NR_getdents64 && __WORDSIZE == 64)
> /* If the condition above is met, __getdents is defined as an alias
> @@ -93,11 +93,13 @@ ssize_t __getdents (int fd, char *buf, size_t nbytes)
> nbytes - size_diff);
>
> dp = (struct dirent *) buf;
> - skdp = kdp = alloca (red_nbytes);
> + skdp = kdp = stack_heap_alloc(red_nbytes);
>
> retval = __syscall_getdents(fd, (unsigned char *)kdp, red_nbytes);
> - if (retval == -1)
> + if (retval == -1) {
> + stack_heap_free(skdp);
> return -1;
> + }
>
> while ((char *) kdp < (char *) skdp + retval) {
> const size_t alignment = __alignof__ (struct dirent);
> @@ -114,6 +116,7 @@ ssize_t __getdents (int fd, char *buf, size_t nbytes)
> if ((char *) dp == buf) {
> /* The buffer the user passed in is too small to hold even
> one entry. */
> + stack_heap_free(skdp);
> __set_errno (EINVAL);
> return -1;
> }
> @@ -130,6 +133,7 @@ ssize_t __getdents (int fd, char *buf, size_t nbytes)
> dp = (struct dirent *) ((char *) dp + new_reclen);
> kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen);
> }
> + stack_heap_free(skdp);
> return (char *) dp - buf;
> }
>
> diff --git a/libc/sysdeps/linux/common/getdents64.c b/libc/sysdeps/linux/common/getdents64.c
> index 37cb4c6..30686f2 100644
> --- a/libc/sysdeps/linux/common/getdents64.c
> +++ b/libc/sysdeps/linux/common/getdents64.c
> @@ -5,7 +5,6 @@
> */
>
> #include <features.h>
> -#include <alloca.h>
> #include <assert.h>
> #include <errno.h>
> #include <dirent.h>
> @@ -17,6 +16,7 @@
> #include <sys/types.h>
> #include <sys/syscall.h>
> #include <bits/kernel_types.h>
> +#include <bits/uClibc_alloc.h>
>
> #if defined __UCLIBC_HAS_LFS__ && defined __NR_getdents64
>
> @@ -52,11 +52,13 @@ ssize_t __getdents64 (int fd, char *buf, size_t nbytes)
> nbytes - size_diff);
>
> dp = (struct dirent64 *) buf;
> - skdp = kdp = alloca (red_nbytes);
> + skdp = kdp = stack_heap_alloc(red_nbytes);
>
> retval = __syscall_getdents64(fd, (unsigned char *)kdp, red_nbytes);
> - if (retval == -1)
> + if (retval == -1) {
> + stack_heap_free(skdp);
> return -1;
> + }
>
> while ((char *) kdp < (char *) skdp + retval) {
> const size_t alignment = __alignof__ (struct dirent64);
> @@ -73,6 +75,7 @@ ssize_t __getdents64 (int fd, char *buf, size_t nbytes)
> if ((char *) dp == buf) {
> /* The buffer the user passed in is too small to hold even
> one entry. */
> + stack_heap_free(skdp);
> __set_errno (EINVAL);
> return -1;
> }
> @@ -89,6 +92,7 @@ ssize_t __getdents64 (int fd, char *buf, size_t nbytes)
> dp = (struct dirent64 *) ((char *) dp + new_reclen);
> kdp = (struct kernel_dirent64 *) (((char *) kdp) + kdp->d_reclen);
> }
> + stack_heap_free(skdp);
> return (char *) dp - buf;
> }
>
Hi Mike,
do you think it could be extended to other part of the library ?
Cheers,
Carmelo
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