Support for specifying a path prefix to run inside an LXC

src/lxcstat.c

@@ -24,16 +24,19 @@ int parseLxcConfigFile(lxcinfo *lxc, char *filedata) {
   strcpy(lxc->hostname, ptr);
 }
 
-int readLxcConfig(lxcinfo *lxc, int lxcid) {
+int readLxcConfig(lxcinfo *lxc, int lxcid, char *pathPrefix) {
   char *fname = malloc(1024);
   char *buffer = malloc(4096);
 
-  sprintf(fname, "/etc/pve/lxc/%d.conf", lxcid);
+  sprintf(fname, "%s/etc/pve/lxc/%d.conf", pathPrefix, lxcid);
   FILE *file = fopen(fname, "rb");
   if (file == NULL) {
-    printf("Failed to open <%s>: %d\n", fname, errno);
+    fprintf(stderr, "Failed to open <%s>: %d\n", fname, errno);
+    free(buffer);
+    free(fname);
     return -1;
   }
+
   fread(buffer, 1, 4096, file);
   fclose(file);
 
@@ -43,14 +46,17 @@ int readLxcConfig(lxcinfo *lxc, int lxcid) {
   return 0;
 }
 
-void getInactiveLXCs(lxcinfo **lxcs) {
+void getInactiveLXCs(lxcinfo **lxcs, char *pathPrefix) {
   struct dirent *pDirent;
   DIR *pDir;
 
+  char *fname = malloc(1024);
+  sprintf(fname, "%s/etc/pve/lxc", pathPrefix);
   // Ensure we can open directory.
-  pDir = opendir("/etc/pve/lxc");
+  pDir = opendir(fname);
   if (pDir == NULL) {
-    printf("Cannot open directory '/etc/pve/lxc'\n");
+    fprintf(stderr, "Cannot open directory '%s'\n", fname);
+    free(fname);
     return;
   }
 
@@ -63,13 +69,14 @@ void getInactiveLXCs(lxcinfo **lxcs) {
     int argc = sscanf(fname, "%d.%s", &lxcid, (char *) extension);
     // ensure it's an LXC config
     if (argc != 2 || strcmp((char *) extension, "conf") != 0) continue;
-    getLXCInfo(lxcs, lxcid);  // don't care about result
+    getLXCInfo(lxcs, lxcid, pathPrefix);  // don't care about result
   }
 
   closedir(pDir);
+  free(fname);
 }
 
-lxcinfo *getLXCInfo(lxcinfo **lxcs, int lxcid) {
+lxcinfo *getLXCInfo(lxcinfo **lxcs, int lxcid, char *pathPrefix) {
   lxcinfo *lxc = *lxcs;
   while (lxc != NULL) {
     if (lxc->lxcid == lxcid) return lxc;
@@ -80,7 +87,7 @@ lxcinfo *getLXCInfo(lxcinfo **lxcs, int lxcid) {
   lxc->lxcid = lxcid;
   lxc->running = 0;
 
-  if (readLxcConfig(lxc, lxcid)) {
+  if (readLxcConfig(lxc, lxcid, pathPrefix)) {
     // failed to read LXC
     free(lxc);
     return NULL;

src/lxcstat.h

@@ -13,7 +13,7 @@ typedef struct _lxc_info {
   char hostname[128];
 } lxcinfo;
 
-lxcinfo *getLXCInfo(lxcinfo **lxcs, int lxcid);
-void getInactiveLXCs(lxcinfo **lxcs);
+lxcinfo *getLXCInfo(lxcinfo **lxcs, int lxcid, char *pathPrefix);
+void getInactiveLXCs(lxcinfo **lxcs, char *pathPrefix);
 
 #endif

src/process.c

@@ -240,16 +240,19 @@ nextProcess:
   }
 }
 
-char *readProcesses(char *procdir) {
+char *readProcesses(char *pathPrefix) {
   int len;
   struct dirent *pDirent;
   DIR *pDir;
 
-  // Ensure we can open directory.
+  char *procdir = malloc(1024);
+  sprintf(procdir, "%s/proc", pathPrefix);
 
+  // Ensure we can open directory.
   pDir = opendir(procdir);
   if (pDir == NULL) {
     printf("Cannot open directory '%s'\n", procdir);
+    free(procdir);
     return NULL;
   }
 
@@ -272,6 +275,7 @@ char *readProcesses(char *procdir) {
 
   while ((pDirent = readdir(pDir)) != NULL) {
     first = pDirent->d_name[0];
+    // Ignore directories that aren't PIDs
     if (first < '0' || first > '9') continue;
 
     if (cur->visited) {
@@ -281,7 +285,7 @@ char *readProcesses(char *procdir) {
       cur = cur->next;
     }
 
-    sprintf(fname, "/proc/%s/status", pDirent->d_name);
+    sprintf(fname, "%s/%s/status", procdir, pDirent->d_name);
     file = fopen(fname, "rb");
     if (file == NULL) continue;
     fread(buffer, 1, 4096, file);
@@ -299,7 +303,7 @@ char *readProcesses(char *procdir) {
 
     if (parseStatFile(cur, buffer)) continue;
 
-    sprintf(fname, "/proc/%s/io", pDirent->d_name);
+    sprintf(fname, "%s/%s/io", procdir, pDirent->d_name);
     file = fopen(fname, "rb");
     if (file == NULL) continue;
     fread(buffer, 1, 4096, file);
@@ -307,7 +311,7 @@ char *readProcesses(char *procdir) {
 
     if (parseIOFile(cur, buffer)) continue;
 
-    sprintf(fname, "/proc/%s/cpuset", pDirent->d_name);
+    sprintf(fname, "%s/%s/cpuset", procdir, pDirent->d_name);
     file = fopen(fname, "rb");
     if (file == NULL) goto nextProcess;
     fread(cur->cpuset, 1, sizeof(cur->cpuset), file);
@@ -318,7 +322,7 @@ char *readProcesses(char *procdir) {
     if (memcmp(cur->cpuset, lxcTag, strlen(lxcTag)) == 0) {
       // Resides in LXC -- read file and tag
       sscanf(cur->cpuset, "/lxc/%d/ns", &cur->lxc);
-      lxcinfo *lxc = getLXCInfo(&lxcs, cur->lxc);
+      lxcinfo *lxc = getLXCInfo(&lxcs, cur->lxc, pathPrefix);
       if (lxc == NULL) {
         printf("Failed to read LXC config <%d>\n", cur->lxc);
       } else {
@@ -340,7 +344,7 @@ nextProcess:
   
   linkFamily(head);
   aggregateStats(head);
-  getInactiveLXCs(&lxcs);
+  getInactiveLXCs(&lxcs, pathPrefix);
 
   int clocks = sysconf(_SC_CLK_TCK);
   char *output = malloc(8 * 1024 * 1024);
@@ -390,6 +394,7 @@ nextProcess:
   }
 
   closedir(pDir);
+  free(procdir);
   free(buffer);
   free(fname);
   return output;

src/process.h

@@ -35,7 +35,7 @@ typedef struct st_process {
     uint64_t cWrite;
 } Process;
 
-char *readProcesses(char *procdir);
+char *readProcesses(char *pathPrefix);
 void aggregateStats(Process *head);
 
 int resetVisits(Process *head);

src/server.c

@@ -44,8 +44,8 @@ void *self_connector_thread(void *arg) {
 
 #define BUFFER_SIZE 1024
 
-void handle_client(int client_socket) {
-  char *data = readProcesses("/proc");
+void handle_client(int client_socket, char *pathPrefix) {
+  char *data = readProcesses(pathPrefix);
   int length = strlen(data);
   printf("Got data of length: %d\n", length);
 
@@ -92,22 +92,32 @@ closeConnection:
 }
 
 int main(int argc, char *argv[]) {
-  if (argc == 1) {
-    char *buf = readProcesses("/proc");
-    if (buf == NULL) return 1;
-    printf(buf);
-    free(buf);
-    return 0;
+  char *portStr = NULL;
+  char *pathPrefix = "";
+
+  for (int i=0; i<argc; i++) {
+    if (strcmp("--port", argv[i]) == 0) {
+      portStr = argv[++i];
+    }
+
+    if (strcmp("--path.rootfs", argv[i]) == 0) {
+      pathPrefix = argv[++i];
+    }
   }
 
-  for (int i=0; i<strlen(argv[1]); i++) {
-    if (argv[1][i] < '0' || argv[1][i] > '9') {
-      fprintf(stderr, "Argument '%s' is not a valid port", argv[1]);
+  if (portStr == NULL) {
+    fprintf(stderr, "Missing required argument --port\n");
+    return 1;
+  }
+
+  for (int i=0; i<strlen(portStr); i++) {
+    if (portStr[i] < '0' || portStr[i] > '9') {
+      fprintf(stderr, "Argument '%s' is not a valid port\n", portStr);
       return 1;
     }
   }
   
-  int port = atoi(argv[1]);
+  int port = atoi(portStr);
   // Set up signal handling
   struct sigaction sa;
   sa.sa_handler = handle_signal;
@@ -166,7 +176,7 @@ int main(int argc, char *argv[]) {
     }
 
     // Handle the client in a separate function
-    handle_client(client_socket);
+    handle_client(client_socket, pathPrefix);
   }
 
   close(client_socket);