Correctly handle spaces in /proc/pid/maps pathnames (#553)

Prior to this change, pathnames were parsed from `/proc/pid/maps` using `s.split(' ')`. This is incorrect, because pathnames may contain spaces.

In practice, on the relevant operating systems, this resulted in truncation of pathnames containing spaces. This lead to a failure resolve any symbols or offsets, which in turn causes the stack trace to be printed containing only `<unknown>`s to the end user.

This PR corrects the parsing code, resolving the issue.

src/symbolize/gimli/parse_running_mmaps_unix.rs

@@ -85,16 +85,37 @@ impl FromStr for MapsEntry {
     // e.g.: "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]"
     // e.g.: "7f5985f46000-7f5985f48000 rw-p 00039000 103:06 76021795                  /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2"
     // e.g.: "35b1a21000-35b1a22000 rw-p 00000000 00:00 0"
+    //
+    // Note that paths may contain spaces, so we can't use `str::split` for parsing (until
+    // Split::remainder is stabilized #77998).
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        let mut parts = s
-            .split(' ') // space-separated fields
-            .filter(|s| s.len() > 0); // multiple spaces implies empty strings that need to be skipped.
-        let range_str = parts.next().ok_or("Couldn't find address")?;
-        let perms_str = parts.next().ok_or("Couldn't find permissions")?;
-        let offset_str = parts.next().ok_or("Couldn't find offset")?;
-        let dev_str = parts.next().ok_or("Couldn't find dev")?;
-        let inode_str = parts.next().ok_or("Couldn't find inode")?;
-        let pathname_str = parts.next().unwrap_or(""); // pathname may be omitted.
+        let (range_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if range_str.is_empty() {
+            return Err("Couldn't find address");
+        }
+
+        let (perms_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if perms_str.is_empty() {
+            return Err("Couldn't find permissions");
+        }
+
+        let (offset_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if offset_str.is_empty() {
+            return Err("Couldn't find offset");
+        }
+
+        let (dev_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if dev_str.is_empty() {
+            return Err("Couldn't find dev");
+        }
+
+        let (inode_str, s) = s.trim_start().split_once(' ').unwrap_or((s, ""));
+        if inode_str.is_empty() {
+            return Err("Couldn't find inode");
+        }
+
+        // Pathname may be omitted in which case it will be empty
+        let pathname_str = s.trim_start();
 
         let hex = |s| usize::from_str_radix(s, 16).map_err(|_| "Couldn't parse hex number");
         let address = if let Some((start, limit)) = range_str.split_once('-') {
@@ -229,4 +250,46 @@ fn check_maps_entry_parsing_32bit() {
             pathname: Default::default(),
         }
     );
+    assert_eq!(
+        "b7c79000-b7e02000 r--p 00000000 08:01 60662705   \
+                /executable/path/with some spaces"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7c79000, 0xb7e02000),
+            perms: ['r', '-', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x08, 0x01),
+            inode: 0x60662705,
+            pathname: "/executable/path/with some spaces".into(),
+        }
+    );
+    assert_eq!(
+        "b7c79000-b7e02000 r--p 00000000 08:01 60662705   \
+                /executable/path/with  multiple-continuous    spaces  "
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7c79000, 0xb7e02000),
+            perms: ['r', '-', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x08, 0x01),
+            inode: 0x60662705,
+            pathname: "/executable/path/with  multiple-continuous    spaces  ".into(),
+        }
+    );
+    assert_eq!(
+        "  b7c79000-b7e02000  r--p  00000000  08:01  60662705   \
+                /executable/path/starts-with-spaces"
+            .parse::<MapsEntry>()
+            .unwrap(),
+        MapsEntry {
+            address: (0xb7c79000, 0xb7e02000),
+            perms: ['r', '-', '-', 'p'],
+            offset: 0x00000000,
+            dev: (0x08, 0x01),
+            inode: 0x60662705,
+            pathname: "/executable/path/starts-with-spaces".into(),
+        }
+    );
 }