WIP: debug

Author: Kobzol

library/std_detect/src/detect/os/linux/auxvec.rs

@@ -118,7 +118,7 @@ pub(crate) fn auxv() -> Result<AuxVec, ()> {
     {
         // If calling getauxval fails, try to read the auxiliary vector from
         // its file:
-        auxv_from_file("/proc/self/auxv")
+        auxv_from_file("/proc/self/auxv").map_err(|_| ())
     }
     #[cfg(not(feature = "std_detect_file_io"))]
     {
@@ -153,10 +153,13 @@ fn getauxval(key: usize) -> Result<usize, ()> {
     Ok(unsafe { ffi_getauxval(key as libc::c_ulong) as usize })
 }
 
+#[cfg(feature = "std_detect_file_io")]
+use alloc::string::String;
+
 /// Tries to read the auxiliary vector from the `file`. If this fails, this
 /// function returns `Err`.
 #[cfg(feature = "std_detect_file_io")]
-pub(super) fn auxv_from_file(file: &str) -> Result<AuxVec, ()> {
+pub(super) fn auxv_from_file(file: &str) -> Result<AuxVec, String> {
     let file = super::read_file(file)?;
 
     // See <https://github.com/torvalds/linux/blob/v5.15/include/uapi/linux/auxvec.h>.
@@ -175,7 +178,7 @@ pub(super) fn auxv_from_file(file: &str) -> Result<AuxVec, ()> {
 /// Tries to interpret the `buffer` as an auxiliary vector. If that fails, this
 /// function returns `Err`.
 #[cfg(feature = "std_detect_file_io")]
-fn auxv_from_buf(buf: &[usize]) -> Result<AuxVec, ()> {
+fn auxv_from_buf(buf: &[usize]) -> Result<AuxVec, String> {
     // Targets with only AT_HWCAP:
     #[cfg(any(
         target_arch = "riscv32",
@@ -220,7 +223,7 @@ fn auxv_from_buf(buf: &[usize]) -> Result<AuxVec, ()> {
     }
     // Suppress unused variable
     let _ = buf;
-    Err(())
+    Err(String::from("hwcap not found"))
 }
 
 #[cfg(test)]

library/std_detect/src/detect/os/linux/mod.rs

@@ -1,19 +1,23 @@
 //! Run-time feature detection on Linux
 //!
 #[cfg(feature = "std_detect_file_io")]
+use alloc::format;
+#[cfg(feature = "std_detect_file_io")]
+use alloc::string::String;
+#[cfg(feature = "std_detect_file_io")]
 use alloc::vec::Vec;
 
 mod auxvec;
 
 #[cfg(feature = "std_detect_file_io")]
-fn read_file(path: &str) -> Result<Vec<u8>, ()> {
-    let mut path = Vec::from(path.as_bytes());
+fn read_file(orig_path: &str) -> Result<Vec<u8>, String> {
+    let mut path = Vec::from(orig_path.as_bytes());
     path.push(0);
 
     unsafe {
         let file = libc::open(path.as_ptr() as *const libc::c_char, libc::O_RDONLY);
         if file == -1 {
-            return Err(());
+            return Err(format!("Cannot open file at {orig_path}"));
         }
 
         let mut data = Vec::new();
@@ -23,7 +27,7 @@ fn read_file(path: &str) -> Result<Vec<u8>, ()> {
             match libc::read(file, spare.as_mut_ptr() as *mut _, spare.len()) {
                 -1 => {
                     libc::close(file);
-                    return Err(());
+                    return Err(format!("Error while reading from file at {orig_path}"));
                 }
                 0 => break,
                 n => data.set_len(data.len() + n as usize),