[PATCH 05/33] Fetching Memory maps

Janani Venkataraman
2014-03-20T09:39:36Z

Fetching virtual memory areas through /proc/pid/maps and storing it in a
linked list in order to populate the program headers and file maps.

Signed-off-by: Janani Venkataraman <jananive@linux.vnet.ibm.com>
---
src/coredump.c | 8 +++++
src/coredump.h | 11 ++++++
src/proc.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 114 insertions(+)

diff --git a/src/coredump.c b/src/coredump.c
index dd9089f..7a559e2 100644
--- a/src/coredump.c
+++ b/src/coredump.c
@@ -183,6 +183,11 @@ int do_coredump(int pid, char *core_file)
if (ret)
goto cleanup;

+ /* Get VMAS */
+ ret = get_vmas(pid, &cp);
+ if (ret)
+ goto cleanup;
+
cleanup:

/* Release the threads */
@@ -191,6 +196,9 @@ cleanup:
if (cp.t_id)
free(cp.t_id);

+ if (cp.vmas)
+ free_maps(cp.vmas);
+
errno = status;

return ret;
diff --git a/src/coredump.h b/src/coredump.h
index 00cb008..291e13b 100644
--- a/src/coredump.h
+++ b/src/coredump.h
@@ -16,8 +16,19 @@ struct pid_stat {
unsigned long long ps_num[NUM_STAT_FEILDS];
};

+/* Structure for maps */
+struct maps {
+ unsigned long long src, dst, offset;
+ char r, w, x;
+ long inode;
+ struct maps *next;
+ char fname[0];
+};
+
/* Structure for the Core of the Process */
struct core_proc {
int thread_count; /* Number of threads */
int *t_id; /* Threads_ids of all the threads */
+ struct maps *vmas; /* VMAs */
+ int phdrs_count; /* Number of Program headers */
};
diff --git a/src/proc.c b/src/proc.c
index fc16d90..a401aa5 100644
--- a/src/proc.c
+++ b/src/proc.c
@@ -25,6 +25,7 @@
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
+#include <string.h>
#include <coredump.h>

/* Get Process Stats */
@@ -136,3 +137,97 @@ char get_thread_status(int tid)

return buff[pos - buff + 2];
}
+
+/* Free Maps */
+void free_maps(struct maps *head)
+{
+ struct maps *tmp;
+
+ while (head) {
+ tmp = head->next;
+ free(head);
+ head = tmp;
+ }
+}
+
+/* Append a new VMA */
+void append_maps(struct maps *new_map, struct core_proc *cp)
+{
+ struct maps *tmp;
+
+ if (cp->vmas == NULL)
+ cp->vmas = new_map;
+ else {
+ tmp = cp->vmas;
+ while (tmp->next != NULL)
+ tmp = tmp->next;
+ tmp->next = new_map;
+ }
+}
+
+/* Collects virtual memory areas */
+int get_vmas(int pid, struct core_proc *cp)
+{
+ char filename[40];
+ char buff[4096];
+ char src[128];
+ char dst[128];
+ char fname[4096];
+ char page_offset[128];
+ char inode[128];
+ char r, w, x;
+ char junk[30];
+ FILE *fin;
+ struct maps *tmp;
+ long tmp_inode;
+
+ snprintf(filename, 40, "/proc/%d/maps", pid);
+ fin = fopen(filename, "r");
+ if (fin == NULL) {
+ status = errno;
+ gencore_log("Failure in fetching Memory Mappings %s.\n",
+ filename);
+ return -1;
+ }
+
+ while (fgets(buff, 4096, fin)) {
+
+ sscanf(buff, "%[^-]%c%s %c%c%c%c %s %s %s %s", src, &junk[0],
+ dst, &r, &w, &x, &junk[0],
+ page_offset, junk, inode, fname);
+
+ tmp_inode = strtol(inode, NULL, 16);
+
+ if (tmp_inode)
+ tmp = malloc(sizeof(struct maps) + strlen(fname) + 1);
+ else
+ tmp = malloc(sizeof(struct maps));
+ if (!tmp) {
+ status = errno;
+ gencore_log("Failure in allocating memory for memory maps.\n");
+ fclose(fin);
+ return -1;
+ }
+
+ tmp->src = strtoull(src, NULL, 16);
+ tmp->dst = strtoull(dst, NULL, 16);
+ tmp->offset = strtoull(page_offset, NULL, 16);
+ tmp->r = r;
+ tmp->w = w;
+ tmp->x = x;
+ tmp->inode = tmp_inode;
+
+ if (tmp->inode != 0)
+ strcpy(tmp->fname, fname);
+
+ tmp->next = NULL;
+ append_maps(tmp, cp);
+ cp->phdrs_count++;
+ }
+
+ /* One extra for the PT_NOTE */
+ cp->phdrs_count++;
+
+ fclose(fin);
+ return 0;
+}