gistfile1.txt

$ file /proc/14207/smaps
/proc/14207/smaps: empty

$ tail /proc/14207/smaps
Shared_Dirty:         0 kB
Private_Clean:        0 kB
Private_Dirty:        8 kB
bf9cc000-bf9e2000 rw-p bf9cc000 00:00 0          [stack]
Size:                88 kB
Rss:                 32 kB
Shared_Clean:         0 kB
Shared_Dirty:         0 kB
Private_Clean:        0 kB
Private_Dirty:       32 kB

$ ls -l /proc/14207/smaps
-r--r--r-- 1 brian brian 0 Apr 23 14:27 /proc/14207/smaps

$ cat /tmp/test.c
#include <stdio.h>
int main() {
    char buf[1024];
    FILE* fp = fopen("/proc/14207/smaps", "rb");
    fread(buf, 1023, 1, fp);
    buf[1023] = '\0';
    printf("%s\n", buf);
    fclose(fp);
    return 0;
}

$ /tmp/test
08048000-081a8000 r-xp 00000000 ca:00 794693     /usr/bin/vim.basic
Size:              1408 kB
Rss:               1220 kB
Shared_Clean:      1144 kB
Shared_Dirty:         0 kB
Private_Clean:       76 kB
Private_Dirty:        0 kB
081a8000-081b4000 rw-p 00160000 ca:00 794693     /usr/bin/vim.basic
Size:                48 kB
Rss:                 44 kB
Shared_Clean:         4 kB
Shared_Dirty:         0 kB
Private_Clean:        0 kB
Private_Dirty:       40 kB
081b4000-082e5000 rw-p 081b4000 00:00 0          [heap]
Size:              1220 kB
Rss:               1160 kB
Shared_Clean:         0 kB
Shared_Dirty:         0 kB
Private_Clean:        0 kB
Private_Dirty:     1160 kB
b7d2c000-b7d35000 r-xp 00000000 ca:00 168        /lib/libnss_files-2.7.so
Size:                36 kB
Rss:                 12 kB
Shared_Clean:        12 kB
Shared_Dirty:         0 kB
Private_Clean:        0 kB
Private_Dirty:        0 kB
b7d35000-b7d37000 rw-p 00008000 ca:00 168        /lib/libnss_files-2.7.so
Size:                 8 kB
Rss:    

$ cat /tmp/test.js
var
  sys = require("sys"),
  fs = require("fs");

sys.puts(fs.readFileSync("/proc/14207/smaps", "binary"));

$ node /tmp/test.js
Error: ESPIPE, Illegal seek
    at Object.readFileSync (fs:79:23)
    at Object.<anonymous> (/tmp/test.js:5:13)
    at Module._compile (module:385:23)
    at module:413:20
    at fs:52:23
    at node.js:164:9

$ node -v
v0.1.91-38-gc9e27b1


What's going on here?

no_pos_0.patch

diff --git a/lib/fs.js b/lib/fs.js
index c3ab698..51cf965 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -73,7 +73,7 @@ fs.readFileSync = function (path, encoding) {
 
   var fd = binding.open(path, process.O_RDONLY, 0666);
   var content = '';
-  var pos = 0;
+  var pos;   // leave undefined to allow reads on unseekable devices
   var r;
 
   while ((r = binding.read(fd, 4*1024, pos, encoding)) && r[0]) {

so /proc/x/smaps is unseekable.

I think node/lib/fs.js should be patched to not use a pos=0 by default.

It makes this work and doesn't change any other functionality that I can see (make test passes).