Attachment 149350 Details for Bug 230850 – Patch on-demand PTRACE_ATTACHING the inferior for /proc/PID/mem read(2).

[patch] Patch on-demand PTRACE_ATTACHING the inferior for /proc/PID/mem read(2).

elfutils-0.126-mem-ptrace3.patch (text/plain), 1.90 KB, created by Jan Kratochvil on 2007-03-06 16:27:06 UTC

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Creator: Jan Kratochvil

Created: 2007-03-06 16:27:06 UTC

Size: 1.90 KB

patch

obsolete

>--- elfutils-0.126-orig/libdwfl/linux-proc-maps.c	2007-01-30 17:19:22.000000000 +0100
>+++ elfutils-0.126/libdwfl/linux-proc-maps.c	2007-03-06 17:10:42.000000000 +0100
>@@ -60,6 +60,8 @@
> #include <unistd.h>
> #include <assert.h>
> #include <endian.h>
>+#include <sys/ptrace.h>
>+#include <sys/wait.h>
> 
> 
> #define PROCMAPSFMT	"/proc/%d/maps"
>@@ -261,12 +263,28 @@ dwfl_linux_proc_report (Dwfl *dwfl, pid_
> }
> INTDEF (dwfl_linux_proc_report)
> 
>+struct read_proc_memory
>+  {
>+    /* PID gets zero on our successful PTRACE_ATTACH.  */
>+    pid_t pid;
>+    int fd;
>+  };
>+
> static ssize_t
>-read_proc_memory (void *arg, void *data, GElf_Addr address,
>+read_proc_memory (void *arg_pointer, void *data, GElf_Addr address,
> 		  size_t minread, size_t maxread)
> {
>-  const int fd = *(const int *) arg;
>-  ssize_t nread = pread64 (fd, data, maxread, (off64_t) address);
>+  struct read_proc_memory *arg = arg_pointer;
>+  ssize_t nread = pread64 (arg->fd, data, maxread, (off64_t) address);
>+  /* We may read /proc/PID/mem only for `PID == getpid()' or if PID is actively
>+     PTRACEd by ourselves.  */
>+  if (nread == -1 && errno == ESRCH && arg->pid != 0
>+      && ptrace (PTRACE_ATTACH, arg->pid, NULL, NULL) == 0)
>+    {
>+      arg->pid = 0;
>+      /* FIXME: Race? waitpid() here locks up for `vdso-test'.  */
>+      nread = pread64 (arg->fd, data, maxread, (off64_t) address);
>+    }
>   if (nread > 0 && (size_t) nread < minread)
>     nread = 0;
>   return nread;
>@@ -319,9 +337,17 @@ dwfl_linux_proc_find_elf (Dwfl_Module *m
>       if (fd < 0)
> 	return -1;
> 
>-      *elfp = elf_from_remote_memory (base, NULL, &read_proc_memory, &fd);
>+      struct read_proc_memory arg;
>+      arg.pid = pid;
>+      arg.fd = fd;
>+      *elfp = elf_from_remote_memory (base, NULL, &read_proc_memory, &arg);
> 
>       close (fd);
>+      if (arg.pid == 0)
>+	{
>+	  if (ptrace (PTRACE_DETACH, pid, NULL, NULL) != 0)
>+	    return -1;
>+	}
> 
>       *file_name = NULL;
>       return -1;

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Attachments on bug 230850: 149185 | 149186 | 149248 | 149350