contrib/elf2dmp: use GLib in PDB processing

Replace POSIX mmap with GLib g_mapped_file_new in PDB processing stage
to make elf2dmp cross-platform. There are no direct POSIX in elf2dmp
after this patch.
Signed-off-by: NViktor Prutyanov <viktor.prutyanov@phystech.edu>
Message-Id: <20181220012441.13694-4-viktor.prutyanov@phystech.edu>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

contrib/elf2dmp/pdb.c

@@ -277,28 +277,18 @@ static void pdb_reader_exit(struct pdb_reader *r)
 
 int pdb_init_from_file(const char *name, struct pdb_reader *reader)
 {
+    GError *gerr = NULL;
     int err = 0;
-    int fd;
     void *map;
-    struct stat st;
 
-    fd = open(name, O_RDONLY, 0);
-    if (fd == -1) {
-        eprintf("Failed to open PDB file \'%s\'\n", name);
+    reader->gmf = g_mapped_file_new(name, TRUE, &gerr);
+    if (gerr) {
+        eprintf("Failed to map PDB file \'%s\'\n", name);
         return 1;
     }
-    reader->fd = fd;
-
-    fstat(fd, &st);
-    reader->file_size = st.st_size;
-
-    map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-    if (map == MAP_FAILED) {
-        eprintf("Failed to map PDB file\n");
-        err = 1;
-        goto out_fd;
-    }
 
+    reader->file_size = g_mapped_file_get_length(reader->gmf);
+    map = g_mapped_file_get_contents(reader->gmf);
     if (pdb_reader_init(reader, map)) {
         err = 1;
         goto out_unmap;
@@ -307,16 +297,13 @@ int pdb_init_from_file(const char *name, struct pdb_reader *reader)
     return 0;
 
 out_unmap:
-    munmap(map, st.st_size);
-out_fd:
-    close(fd);
+    g_mapped_file_unref(reader->gmf);
 
     return err;
 }
 
 void pdb_exit(struct pdb_reader *reader)
 {
-    munmap(reader->ds.header, reader->file_size);
-    close(reader->fd);
+    g_mapped_file_unref(reader->gmf);
     pdb_reader_exit(reader);
 }

contrib/elf2dmp/pdb.h

@@ -216,7 +216,7 @@ typedef struct pdb_seg {
 #define IMAGE_FILE_MACHINE_AMD64 0x8664
 
 struct pdb_reader {
-    int fd;
+    GMappedFile *gmf;
     size_t file_size;
     struct {
         PDB_DS_HEADER *header;