Use NT_FILE to get backing file names if available

A Linux core dump passes backing file names for LOAD segments. The coredump
library should take advantage of them if they are present.

8 files changed, 196 insertions, 45 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 43a61ff1..f295c866 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -94,7 +94,9 @@ if(UNW_CMAKE_TARGET_LINUX)
     SET(libunwind_la_SOURCES_x86_64_os_local    x86_64/Los-linux.c)
     SET(libunwind_la_SOURCES_arm_os             arm/Gos-linux.c)
     SET(libunwind_la_SOURCES_arm_os_local       arm/Los-linux.c)
-    list(APPEND libunwind_coredump_la_SOURCES   coredump/_UCD_access_reg_linux.c)
+    list(APPEND libunwind_coredump_la_SOURCES   coredump/_UCD_access_reg_linux.c
+                                                coredump/_UCD_get_threadinfo_prstatus.c
+                                                coredump/_UCD_get_mapinfo_linux.c)
 elseif(UNW_CMAKE_TARGET_FREEBSD)
     SET(libunwind_la_SOURCES_os                 ${libunwind_la_SOURCES_os_freebsd})
     SET(libunwind_la_SOURCES_os_local           ${libunwind_la_SOURCES_os_freebsd_local})
@@ -105,7 +107,9 @@ elseif(UNW_CMAKE_TARGET_FREEBSD)
     SET(libunwind_la_SOURCES_x86_64_os_local    x86_64/Los-freebsd.c)
     SET(libunwind_la_SOURCES_arm_os             arm/Gos-freebsd.c)
     SET(libunwind_la_SOURCES_arm_os_local       arm/Los-freebsd.c)
-    list(APPEND libunwind_coredump_la_SOURCES   coredump/_UCD_access_reg_freebsd.c)
+    list(APPEND libunwind_coredump_la_SOURCES   coredump/_UCD_access_reg_freebsd.c
+                                                coredump/_UCD_get_threadinfo_prstatus.c
+                                                coredump/_UCD_get_mapinfo_generic.c)
 elseif(UNW_CMAKE_HOST_SUNOS)
     SET(libunwind_la_SOURCES_os                 ${libunwind_la_SOURCES_os_solaris})
     SET(libunwind_la_SOURCES_os_local           ${libunwind_la_SOURCES_os_solaris_local})
diff --git a/src/Makefile.am b/src/Makefile.am
index 4d47203e..4b146bcd 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -521,7 +521,8 @@ if OS_LINUX
  libunwind_la_SOURCES_arm_os          = arm/Gos-linux.c
  libunwind_la_SOURCES_arm_os_local    = arm/Los-linux.c
  libunwind_coredump_la_SOURCES += coredump/_UCD_access_reg_linux.c
- libunwind_coredump_la_SOURCES += coredump/_UCD_get_threadinfo_linux.c
+ libunwind_coredump_la_SOURCES += coredump/_UCD_get_threadinfo_prstatus.c
+ libunwind_coredump_la_SOURCES += coredump/_UCD_get_mapinfo_linux.c
 endif
 
 if OS_HPUX
@@ -540,6 +541,8 @@ if OS_FREEBSD
  libunwind_la_SOURCES_arm_os          = arm/Gos-freebsd.c
  libunwind_la_SOURCES_arm_os_local    = arm/Los-freebsd.c
  libunwind_coredump_la_SOURCES += coredump/_UCD_access_reg_freebsd.c
+ libunwind_coredump_la_SOURCES += coredump/_UCD_get_threadinfo_prstatus.c
+ libunwind_coredump_la_SOURCES += coredump/_UCD_get_mapinfo_generic.c
 endif
 
 if OS_SOLARIS
diff --git a/src/coredump/_UCD_create.c b/src/coredump/_UCD_create.c
index 3c0345e2..afb300eb 100644
--- a/src/coredump/_UCD_create.c
+++ b/src/coredump/_UCD_create.c
@@ -181,6 +181,12 @@ _UCD_create(const char *filename)
 		goto err;
 	}
 
+    ret = _UCD_get_mapinfo(ui, phdrs, size);
+    if (ret != UNW_ESUCCESS) {
+		Debug(0, "failure retrieving file mapping from core file\n");
+		goto err;
+	}
+
     if (unwi_debug_level > 1)
 	  {
 		coredump_phdr_t *cur = phdrs;
@@ -295,41 +301,6 @@ int _UCD_add_backing_file_at_segment(struct UCD_info *ui, int phdr_no, const cha
     }
 //TODO: else loudly complain? Maybe even fail?
 
-  if (phdr->p_filesz != 0)
-    {
-//TODO: loop and compare in smaller blocks
-      char *core_buf = malloc(phdr->p_filesz);
-      char *file_buf = malloc(phdr->p_filesz);
-      if (lseek(ui->coredump_fd, phdr->p_offset, SEEK_SET) != (off_t)phdr->p_offset
-       || (uoff_t)read(ui->coredump_fd, core_buf, phdr->p_filesz) != phdr->p_filesz
-      )
-        {
-          Debug(0, "Error reading from coredump file\n");
- err_read:
-          free(core_buf);
-          free(file_buf);
-          goto err;
-        }
-      if ((uoff_t)read(fd, file_buf, phdr->p_filesz) != phdr->p_filesz)
-        {
-          Debug(0, "Error reading from '%s'\n", filename);
-          goto err_read;
-        }
-      int r = memcmp(core_buf, file_buf, phdr->p_filesz);
-      free(core_buf);
-      free(file_buf);
-      if (r != 0)
-        {
-          Debug(1, "Note: phdr[%u] first %lld bytes in core dump and in file do not match\n",
-                                phdr_no, (unsigned long long)phdr->p_filesz
-          );
-        } else {
-          Debug(1, "Note: phdr[%u] first %lld bytes in core dump and in file match\n",
-                                phdr_no, (unsigned long long)phdr->p_filesz
-          );
-        }
-    }
-
   /* Success */
   return 0;
 
diff --git a/src/coredump/_UCD_get_mapinfo_generic.c b/src/coredump/_UCD_get_mapinfo_generic.c
new file mode 100644
index 00000000..19945d72
--- /dev/null
+++ b/src/coredump/_UCD_get_mapinfo_generic.c
@@ -0,0 +1,34 @@
+/**
+ * Extract filemap info from a coredump (generic)
+ */
+/*
+ This file is part of libunwind.
+ 
+ Permission is hereby granted, free of charge, to any person obtaining a copy of
+ this software and associated documentation files (the "Software"), to deal in
+ the Software without restriction, including without limitation the rights to
+ use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+ of the Software, and to permit persons to whom the Software is furnished to do
+ so, subject to the following conditions:
+ 
+ The above copyright notice and this permission notice shall be included in all
+ copies or substantial portions of the Software.
+ 
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ SOFTWARE.
+*/
+#include "_UCD_internal.h"
+
+
+int
+_UCD_get_mapinfo(struct UCD_info *ui, coredump_phdr_t *phdrs, unsigned phdr_size)
+{
+  int ret = UNW_ESUCCESS; /* it's OK if there are no file mappings */
+
+  return ret;
+}
diff --git a/src/coredump/_UCD_get_mapinfo_linux.c b/src/coredump/_UCD_get_mapinfo_linux.c
new file mode 100644
index 00000000..8dc7709f
--- /dev/null
+++ b/src/coredump/_UCD_get_mapinfo_linux.c
@@ -0,0 +1,132 @@
+/**
+ * Extract filemap info from a coredump (Linux and similar)
+ */
+/*
+ This file is part of libunwind.
+ 
+ Permission is hereby granted, free of charge, to any person obtaining a copy of
+ this software and associated documentation files (the "Software"), to deal in
+ the Software without restriction, including without limitation the rights to
+ use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+ of the Software, and to permit persons to whom the Software is furnished to do
+ so, subject to the following conditions:
+ 
+ The above copyright notice and this permission notice shall be included in all
+ copies or substantial portions of the Software.
+ 
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ SOFTWARE.
+*/
+#include "_UCD_internal.h"
+
+
+/**
+ * The format of the NT_FILE note is not well documented, but it goes something
+ * like this.
+ *
+ * The note has a header containing the @i count of the number of file maps, plus a
+ * value of the size of the offset field in each map. Since we don;t care about
+ * the offset field in a core file, there is no further information available on
+ * exactly what the means.
+ *
+ * Following the header are @count mapinfo structures. The mapinfo structure consists of
+ * a start address, and end address, and some wacky offset thing.  The start and
+ * end address are the virtual addresses of a LOAD segment that was mapped from
+ * the named file.
+ *
+ * Following the array of mapinfo structures is a block of null-terminated C strings
+ * containing the mapped file names.  They are ordered correspondingly to each
+ * entry in the map structure array.
+ */
+typedef struct {
+  unsigned long count;
+  unsigned long pagesz;
+} linux_mapinfo_hdr_t;
+
+typedef struct {
+  unsigned long start;
+  unsigned long end;
+  unsigned long offset;
+} linux_mapinfo_t;
+
+
+/**
+ * Map a file note to program headers
+ *
+ * If a NT_FILE note is recognized, parse it and add the resulting backing files
+ * to the program header list.
+ *
+ * Any file names that end in the string "(deleted)" are ignored.
+ */
+static int
+_handle_file_note(uint32_t n_namesz, uint32_t n_descsz, uint32_t n_type, char *name, uint8_t *desc, void *arg)
+{
+  struct UCD_info *ui = (struct UCD_info *)arg;
+  if (n_type == NT_FILE)
+  {
+    Debug(0, "found a PT_FILE note\n");
+    static const char * deleted = "(deleted)";
+    size_t deleted_len = strlen(deleted);
+    static const size_t mapinfo_offset = sizeof(linux_mapinfo_hdr_t);
+
+    linux_mapinfo_hdr_t *mapinfo = (linux_mapinfo_hdr_t *)desc;
+    linux_mapinfo_t *maps = (linux_mapinfo_t *)(desc + mapinfo_offset);
+    char *strings = (char *)(desc + mapinfo_offset + sizeof(linux_mapinfo_t)*mapinfo->count);
+    for (unsigned long i = 0; i < mapinfo->count; ++i)
+    {
+      size_t len = strlen(strings);
+      for (unsigned p = 0; p < ui->phdrs_count; ++p)
+      {
+      	if (ui->phdrs[p].p_type == PT_LOAD
+      	  && maps[i].start >= ui->phdrs[p].p_vaddr
+      	  && maps[i].end <= ui->phdrs[p].p_vaddr + ui->phdrs[p].p_filesz)
+	{
+	  if (len > deleted_len && memcmp(strings + len - deleted_len, deleted, deleted_len))
+	  {
+	    _UCD_add_backing_file_at_segment(ui, p, strings);
+	  }
+	  break;
+	}
+      }
+      strings += (len + 1);
+    }
+  }
+  return UNW_ESUCCESS;
+}
+
+
+/**
+ * Get filemap info from core file (Linux and similar)
+ *
+ * If there is a mapinfo not in the core file, map its contents to the phdrs.
+ *
+ * Since there may or may not be any mapinfo notes it's OK for this function to
+ * fail.
+ */
+int
+_UCD_get_mapinfo(struct UCD_info *ui, coredump_phdr_t *phdrs, unsigned phdr_size)
+{
+  int ret = UNW_ESUCCESS; /* it's OK if there are no file mappings */
+
+  for (unsigned i = 0; i < phdr_size; ++i)
+  {
+    if (phdrs[i].p_type == PT_NOTE)
+    {
+      uint8_t *segment;
+      size_t segment_size;
+      ret = _UCD_elf_read_segment(ui, &phdrs[i], &segment, &segment_size);
+      if (ret == UNW_ESUCCESS)
+      {
+      	_UCD_elf_visit_notes(segment, segment_size, _handle_file_note, ui);
+      	free(segment);
+      }
+    }
+  }
+
+  return ret;
+}
diff --git a/src/coredump/_UCD_get_threadinfo_linux.c b/src/coredump/_UCD_get_threadinfo_prstatus.c
index d218a079..45552566 100644
--- a/src/coredump/_UCD_get_threadinfo_linux.c
+++ b/src/coredump/_UCD_get_threadinfo_prstatus.c
@@ -1,5 +1,5 @@
 /**
- * Extract threadinfo from a coredump (Linux and similar)
+ * Extract threadinfo from a coredump (targets with NT_PRSTATUS)
  */
 /*
  This file is part of libunwind.
@@ -70,7 +70,7 @@ _save_thread_notes(uint32_t n_namesz, uint32_t n_descsz, uint32_t n_type, char *
 
 
 /**
- * Get thread info from core file (Linux and similar)
+ * Get thread info from core file
  *
  * On Linux threads are emulated by cloned processes sharing an address space
  * and the process information is described by a note in the core file of type
diff --git a/src/coredump/_UCD_internal.h b/src/coredump/_UCD_internal.h
index 354dbc1d..f5150205 100644
--- a/src/coredump/_UCD_internal.h
+++ b/src/coredump/_UCD_internal.h
@@ -101,9 +101,11 @@ typedef int (*note_visitor_t)(uint32_t, uint32_t, uint32_t, char *, uint8_t *, v
 
 
 coredump_phdr_t * _UCD_get_elf_image(struct UCD_info *ui, unw_word_t ip);
-int _UCD_get_threadinfo(struct UCD_info *ui, coredump_phdr_t *phdrs, unsigned phdr_size);
+
 int _UCD_elf_read_segment(struct UCD_info *ui, coredump_phdr_t *phdr, uint8_t **segment, size_t *segment_size);
 int _UCD_elf_visit_notes(uint8_t *segment, size_t segment_size, note_visitor_t visit, void *arg);
+int _UCD_get_threadinfo(struct UCD_info *ui, coredump_phdr_t *phdrs, unsigned phdr_size);
+int _UCD_get_mapinfo(struct UCD_info *ui, coredump_phdr_t *phdrs, unsigned phdr_size);
 
 
 #endif
diff --git a/tests/test-coredump-unwind.c b/tests/test-coredump-unwind.c
index 1a3c130f..93d9a0ee 100644
--- a/tests/test-coredump-unwind.c
+++ b/tests/test-coredump-unwind.c
@@ -322,7 +322,7 @@ main(int argc UNUSED, char **argv)
       if (*colon != ':')
         error_msg_and_die("Bad format: '%s'", *argv);
       if (_UCD_add_backing_file_at_vaddr(ui, vaddr, colon + 1) < 0)
-        error_msg_and_die("Can't add backing file '%s'", colon + 1);
+        error_msg("Can't add backing file '%s'", colon + 1);
       argv++;
     }
 
@@ -338,11 +338,16 @@ main(int argc UNUSED, char **argv)
       if (ret < 0)
         error_msg_and_die("unw_get_proc_info(ip=0x%lx) failed: ret=%d\n", (long) ip, ret);
 
-      if (!testcase)
-        printf("\tip=0x%08lx proc=%08lx-%08lx handler=0x%08lx lsda=0x%08lx\n",
+      if (!testcase) {
+        char proc_name[128];
+        unw_word_t off;
+        unw_get_proc_name(&c, proc_name, sizeof(proc_name), &off);
+
+        printf("\tip=0x%08lx proc=%08lx-%08lx handler=0x%08lx lsda=0x%08lx %s\n",
 				(long) ip,
 				(long) pi.start_ip, (long) pi.end_ip,
-				(long) pi.handler, (long) pi.lsda);
+				(long) pi.handler, (long) pi.lsda, proc_name);
+	  }
 
       if (testcase && test_cur < TEST_FRAMES)
         {