Re: [PATCH 1/8] bsd-user/elfload.c: Replaced calls to malloc/free with GLib variants

[Alex Bennée]

Mahmoud Mandour <ma.mandourr@gmail.com> writes:

> Replaced the calls to malloc(), realloc(), and free() to their
> equivalents in GLib's allocation functions in various places.
>
> Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
> ---
>  bsd-user/elfload.c | 74 +++++++++++++++++++++++-----------------------
>  1 file changed, 37 insertions(+), 37 deletions(-)
>
> diff --git a/bsd-user/elfload.c b/bsd-user/elfload.c
> index 5f4d824d78..7b0793693b 100644
> --- a/bsd-user/elfload.c
> +++ b/bsd-user/elfload.c
> @@ -867,8 +867,7 @@ static abi_ulong load_elf_interp(struct elfhdr * 
> interp_elf_ex,
>          if (sizeof(struct elf_phdr) * interp_elf_ex->e_phnum > 
> TARGET_PAGE_SIZE)
>              return ~(abi_ulong)0UL;
>  
> -        elf_phdata =  (struct elf_phdr *)
> -                malloc(sizeof(struct elf_phdr) * interp_elf_ex->e_phnum);
> +        elf_phdata = g_try_new(struct elf_phdr,
> interp_elf_ex->ephnum)

Given this is start-up code I think you could use g_new instead of
g_try_new. As it will abort on no memory you can avoid the early return
check bellow. Also is elf_phdata never persists beyond this function you
could use g_autofree (and use g_steal_pointer on the one case when it is
returned if you need it)

>  
>          if (!elf_phdata)
>            return ~((abi_ulong)0UL);
> @@ -878,7 +877,7 @@ static abi_ulong load_elf_interp(struct elfhdr * 
> interp_elf_ex,
>           * we will be doing the wrong thing.
>           */
>          if (interp_elf_ex->e_phentsize != sizeof(struct elf_phdr)) {
> -            free(elf_phdata);
> +            g_free(elf_phdata);
>              return ~((abi_ulong)0UL);
>          }
>  
> @@ -891,7 +890,7 @@ static abi_ulong load_elf_interp(struct elfhdr * 
> interp_elf_ex,
>          if (retval < 0) {
>                  perror("load_elf_interp");
>                  exit(-1);
> -                free (elf_phdata);
> +                g_free(elf_phdata);
>                  return retval;
>          }
>  #ifdef BSWAP_NEEDED
> @@ -940,7 +939,7 @@ static abi_ulong load_elf_interp(struct elfhdr * 
> interp_elf_ex,
>              if (error == -1) {
>                /* Real error */
>                close(interpreter_fd);
> -              free(elf_phdata);
> +              g_free(elf_phdata);
>                return ~((abi_ulong)0UL);
>              }
>  
> @@ -983,7 +982,7 @@ static abi_ulong load_elf_interp(struct elfhdr * 
> interp_elf_ex,
>                          PROT_READ|PROT_WRITE|PROT_EXEC,
>                          MAP_FIXED|MAP_PRIVATE|MAP_ANON, -1, 0);
>          }
> -        free(elf_phdata);
> +        g_free(elf_phdata);
>

That would allow you to get rid of a lot of free/g_frees

I would also split this patch, one for each function you convert.

>          *interp_load_addr = load_addr;
>          return ((abi_ulong) interp_elf_ex->e_entry) + load_addr;
> @@ -1064,24 +1063,24 @@ static void load_symbols(struct elfhdr *hdr, int fd)
>  
>   found:
>      /* Now know where the strtab and symtab are.  Snarf them. */
> -    s = malloc(sizeof(*s));
> -    syms = malloc(symtab.sh_size);
> +    s = g_try_malloc(sizeof(*s));
> +    syms = g_try_malloc(symtab.sh_size);
>      if (!syms) {
> -        free(s);
> +        g_free(s);
>          return;
>      }
> -    s->disas_strtab = strings = malloc(strtab.sh_size);
> +    s->disas_strtab = strings = g_malloc(strtab.sh_size);
>      if (!s->disas_strtab) {
> -        free(s);
> -        free(syms);
> +        g_free(s);
> +        g_free(syms);
>          return;
>      }
>  
>      lseek(fd, symtab.sh_offset, SEEK_SET);
>      if (read(fd, syms, symtab.sh_size) != symtab.sh_size) {
> -        free(s);
> -        free(syms);
> -        free(strings);
> +        g_free(s);
> +        g_free(syms);
> +        g_free(strings);
>          return;
>      }
>  
> @@ -1113,11 +1112,11 @@ static void load_symbols(struct elfhdr *hdr, int fd)
>          that we threw away.  Whether or not this has any effect on the
>          memory allocation depends on the malloc implementation and how
>          many symbols we managed to discard. */
> -    new_syms = realloc(syms, nsyms * sizeof(*syms));
> +    new_syms = g_try_realloc(syms, nsyms * sizeof(*syms));
>      if (new_syms == NULL) {
> -        free(s);
> -        free(syms);
> -        free(strings);
> +        g_free(s);
> +        g_free(syms);
> +        g_free(strings);
>          return;
>      }
>      syms = new_syms;
> @@ -1126,9 +1125,9 @@ static void load_symbols(struct elfhdr *hdr, int fd)
>  
>      lseek(fd, strtab.sh_offset, SEEK_SET);
>      if (read(fd, strings, strtab.sh_size) != strtab.sh_size) {
> -        free(s);
> -        free(syms);
> -        free(strings);
> +        g_free(s);
> +        g_free(syms);
> +        g_free(strings);
>          return;
>      }
>      s->disas_num_syms = nsyms;
> @@ -1190,7 +1189,8 @@ int load_elf_binary(struct linux_binprm * bprm, struct 
> target_pt_regs * regs,
>      }
>  
>      /* Now read in all of the header information */
> -    elf_phdata = (struct elf_phdr 
> *)malloc(elf_ex.e_phentsize*elf_ex.e_phnum);
> +    elf_phdata =
> +        (struct elf_phdr *)g_try_malloc(elf_ex.e_phentsizei * 
> elf_ex.e_phnum);
>      if (elf_phdata == NULL) {
>          return -ENOMEM;
>      }
> @@ -1204,7 +1204,7 @@ int load_elf_binary(struct linux_binprm * bprm, struct 
> target_pt_regs * regs,
>      if (retval < 0) {
>          perror("load_elf_binary");
>          exit(-1);
> -        free (elf_phdata);
> +        g_free(elf_phdata);
>          return -errno;
>      }
>  
> @@ -1231,8 +1231,8 @@ int load_elf_binary(struct linux_binprm * bprm, struct 
> target_pt_regs * regs,
>          if (elf_ppnt->p_type == PT_INTERP) {
>              if ( elf_interpreter != NULL )
>              {
> -                free (elf_phdata);
> -                free(elf_interpreter);
> +                g_free(elf_phdata);
> +                g_free(elf_interpreter);
>                  close(bprm->fd);
>                  return -EINVAL;
>              }
> @@ -1242,10 +1242,10 @@ int load_elf_binary(struct linux_binprm * bprm, 
> struct target_pt_regs * regs,
>               * is an a.out format binary
>               */
>  
> -            elf_interpreter = (char *)malloc(elf_ppnt->p_filesz);
> +            elf_interpreter = (char *)g_try_malloc(elf_ppnt->p_filesz);
>  
>              if (elf_interpreter == NULL) {
> -                free (elf_phdata);
> +                g_free(elf_phdata);
>                  close(bprm->fd);
>                  return -ENOMEM;
>              }
> @@ -1298,8 +1298,8 @@ int load_elf_binary(struct linux_binprm * bprm, struct 
> target_pt_regs * regs,
>              if (retval < 0) {
>                  perror("load_elf_binary3");
>                  exit(-1);
> -                free (elf_phdata);
> -                free(elf_interpreter);
> +                g_free(elf_phdata);
> +                g_free(elf_interpreter);
>                  close(bprm->fd);
>                  return retval;
>              }
> @@ -1323,8 +1323,8 @@ int load_elf_binary(struct linux_binprm * bprm, struct 
> target_pt_regs * regs,
>          }
>  
>          if (!interpreter_type) {
> -            free(elf_interpreter);
> -            free(elf_phdata);
> +            g_free(elf_interpreter);
> +            g_free(elf_phdata);
>              close(bprm->fd);
>              return -ELIBBAD;
>          }
> @@ -1346,8 +1346,8 @@ int load_elf_binary(struct linux_binprm * bprm, struct 
> target_pt_regs * regs,
>              }
>          }
>          if (!bprm->p) {
> -            free(elf_interpreter);
> -            free (elf_phdata);
> +            g_free(elf_interpreter);
> +            g_free(elf_phdata);
>              close(bprm->fd);
>              return -E2BIG;
>          }
> @@ -1486,17 +1486,17 @@ int load_elf_binary(struct linux_binprm * bprm, 
> struct target_pt_regs * regs,
>          reloc_func_desc = interp_load_addr;
>  
>          close(interpreter_fd);
> -        free(elf_interpreter);
> +        g_free(elf_interpreter);
>  
>          if (elf_entry == ~((abi_ulong)0UL)) {
>              printf("Unable to load interpreter\n");
> -            free(elf_phdata);
> +            g_free(elf_phdata);
>              exit(-1);
>              return 0;
>          }
>      }
>  
> -    free(elf_phdata);
> +    g_free(elf_phdata);
>  
>      if (qemu_log_enabled())
>          load_symbols(&elf_ex, bprm->fd);


-- 
Alex Bennée