feat: Allow Syscall name extraction on generic Linux

.gitignore

@@ -0,0 +1,3 @@
+main.o
+syscall_nr.h
+ministrace

Makefile

@@ -1,10 +1,12 @@
 all: ministrace
 
-ministrace: syscall_nr.h main.o
+.PHONY: run
+
+ministrace: syscall_nr.h main.c
 	$(CC) -o $@ $^
 
 %.o: %.c
 	$(CC) -c $^
 
 syscall_nr.h:
-	python get_syscalls.py /usr/include/asm/unistd_64.h > syscall_nr.h
+	./get_syscalls.sh

README.md

@@ -4,6 +4,9 @@ This repository contains a basic reimplementation of the `strace` tool.
 
 ## Building
 
+Before building, ensure that you have the Linux headers installed on your system.
+On Debian-based systems, try installing them with apt: `sudo apt install linux-headers-xxxx`.
+
 Run `make all` to build `ministrace`. Run `./ministrace <program> <args>` to
 trace `program`.
 
@@ -15,3 +18,5 @@ macros in `unistd_64.h` to generate a mapping.
 Note that we have no information on the number and types of arguments to
 syscalls. The two possible approaches here seem to be parsing syscall
 implementations or manually mapping syscall numbers to argument count and types.
+
+NOTE: The syscall extraction was tested on both Debian, Fedora and NixOS.

get_syscalls.py

@@ -1,5 +1,6 @@
 import sys
 
+
 def main():
     syscalls = dict()
     with open(sys.argv[1], "r") as fp:
@@ -9,14 +10,14 @@ def main():
                 definition = line[13:]
                 parts = definition.split()
                 syscalls[int(parts[1])] = parts[0]
-                print("void populate_syscalls() {")
+
         print("#define SYSCALL_NAME(nr) SYSCALLS[nr]")
         print(f"char *SYSCALLS[{max(syscalls.keys())}];")
-    print("}")
         print("void populate_syscalls() {")
         for (k, v) in syscalls.items():
             print(f"    SYSCALLS[{k}] = \"{v}\";")
         print("}")
 
+
 if __name__ == "__main__":
     main()

get_syscalls.sh

@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+
+GCC="gcc"
+SED="sed"
+
+HEADER_FILE="unistd_64.h"
+
+ensure_avail() {
+   command=$1
+   if ! which "${command}" > /dev/null; then
+       echo "ERROR: the ${command} is not available on your system."
+       exit 1
+   fi
+
+   echo "[OK] ${command} available."
+}
+
+get_header_locations() {
+    RAW=$(LC_ALL=C "${GCC}" -v -E -xc - </dev/null 2>&1 | LC_ALL=C "${SED}" -ne '/starts here/,/End of/p')
+
+    for word in $RAW; do
+        if [[ $word == /* ]]; then
+            echo "$word"
+        fi
+    done
+}
+
+ensure_avail gcc
+ensure_avail sed
+
+headers=$(get_header_locations)
+
+CANDIDATES=""
+
+for header in $headers; do
+    echo "CHECKING include dir ${header}..."
+    matches=$(find "${header}" -name "${HEADER_FILE}")
+
+    if [ "${#matches}" != "0" ]; then
+        echo "[OK] FOUND ${matches}"
+        CANDIDATES+=" ${matches}"
+    fi
+
+done
+
+
+if [ "${#CANDIDATES}"  = "0" ]; then
+    echo "[ERR] none of the search directories contains ${HEADER_FILE}"
+    exit 1
+fi
+
+success=0
+
+echo "CAN: $CANDIDATES"
+
+for candidate in $CANDIDATES; do
+    OUTPUT=""
+
+    if ! OUTPUT=$(python3 ./get_syscalls.py "${candidate}" 2>&1 ); then
+        echo "[ERR] File ${candidate} is invalid."
+    else
+        echo "[OK] File ${candidate} is valid."
+        success=1
+        break
+    fi
+done
+
+if [ $success -eq 0 ]; then
+    echo "${OUTPUT}"
+    echo "[ERR] could not extract syscalls: all sources failed"
+    exit 1
+else
+    echo "$OUTPUT" > ./syscall_nr.h
+fi