A lot of changes were suggested by Chris.

ExecveHandler.c:
* Use "" instead of <> for LLVM include files
* Use raw I/O, we don't need buffering
* Set errno = 0 before using open()
* strlen() doesn't count NULL terminator in its size
* Use memcmp() instead of strcmp()
* Return result of the real execve(), not 0
* Search for path to bytecode file if not absolute/relative path

SysUtils.c:
* Convert all comments to C-style
* Stop using `bool', use `unsigned' instead

SysUtils.h:
* Stop using `bool', use `unsigned' instead
* Updated comment to FindExecutable()

README.txt:
* Describe the goal of LLEE and an application


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7911 91177308-0d34-0410-b5e6-96231b3b80d8

tools/llee/ExecveHandler.c

@@ -6,9 +6,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "SysUtils.h"
-#include <Config/dlfcn.h>
-#include <Config/errno.h>
-#include <Config/stdlib.h>
+#include "Config/dlfcn.h"
+#include "Config/errno.h"
+#include "Config/stdlib.h"
+#include "Config/unistd.h"
+#include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
 
@@ -52,18 +54,17 @@ int executeProgram(const char *filename, char *const argv[], char *const envp[])
 int execve(const char *filename, char *const argv[], char *const envp[])
 {
   /* Open the file, test to see if first four characters are "llvm" */
-  char header[4];
-  FILE *file = fopen(filename, "r");
+  size_t headerSize = strlen(llvmHeader);
+  char header[headerSize];
+  errno = 0;
+  int file = open(filename, O_RDONLY);
   /* Check validity of `file' */
-  if (errno) { return errno; }
+  if (errno) return EIO;
   /* Read the header from the file */
-  size_t headerSize = strlen(llvmHeader) - 1; // ignore the NULL terminator
-  size_t bytesRead = fread(header, sizeof(char), headerSize, file);
-  fclose(file);
-  if (bytesRead != headerSize) { 
-    return EIO;
-  }
-  if (!strncmp(llvmHeader, header, headerSize)) {
+  ssize_t bytesRead = read(file, header, headerSize);
+  close(file);
+  if (bytesRead != headerSize) return EIO;
+  if (!memcmp(llvmHeader, header, headerSize)) {
     /* 
      * This is a bytecode file, so execute the JIT with the program and
      * parameters.
@@ -72,21 +73,30 @@ int execve(const char *filename, char *const argv[], char *const envp[])
     for (argvSize = 0, idx = 0; argv[idx] && argv[idx][0]; ++idx)
       ++argvSize;
     char **LLIargs = (char**) malloc(sizeof(char*) * (argvSize+2));
+    char *BCpath;
+    /* 
+     * If the program is specified with a relative or absolute path, 
+     * then just use the path and filename as is, otherwise search for it.
+     */
+    if (filename[0] != '.' && filename[0] != '/')
+      BCpath = FindExecutable(filename);
+    else
+      BCpath = (char*) filename;
+    if (!BCpath) {
+      fprintf(stderr, "Cannot find path to `%s', exiting.\n", filename);
+      return -1;
+    }
     char *LLIpath = FindExecutable("lli");
     if (!LLIpath) {
       fprintf(stderr, "Cannot find path to `lli', exiting.\n");
       return -1;
     }
     LLIargs[0] = LLIpath;
-    for (idx = 0; idx != argvSize; ++idx)
+    LLIargs[1] = BCpath;
+    for (idx = 1; idx != argvSize; ++idx)
       LLIargs[idx+1] = argv[idx];
     LLIargs[argvSize + 1] = '\0';
-    /*
-    for (idx = 0; idx != argvSize+2; ++idx)
-      printf("LLI args[%d] = \"%s\"\n", idx, LLIargs[idx]);
-    */
     return executeProgram(LLIpath, LLIargs, envp);
   }
-  executeProgram(filename, argv, envp); 
-  return 0;
+  return executeProgram(filename, argv, envp); 
 }

tools/llee/README.txt

@@ -0,0 +1,12 @@
+              LLEE: (LL)VM (E)xecution (E)nvironment
+
+This tool presents a virtual execution environment for LLVM programs. By
+preloading a shared object which defines a custom execve() functions, we can
+execute bytecode files with the JIT directly, without the user ever thinking
+about it.
+
+Thus, a user can freely run any program, native or LLVM bytecode, transparently,
+and without even being aware of it.
+
+To use LLEE, run `./llee <native_program>', a good choice is a shell. Anything
+started within that program will be affected by the execve() replacement.

tools/llee/SysUtils.c

@@ -15,16 +15,17 @@
 #include <stdlib.h>
 #include <string.h>
 
-/// isExecutableFile - This function returns true if the filename specified
-/// exists and is executable.
-///
-bool isExecutableFile(const char *ExeFileName) {
+/*
+ * isExecutableFile - This function returns true if the filename specified
+ * exists and is executable.
+ */
+unsigned isExecutableFile(const char *ExeFileName) {
   struct stat Buf;
   if (stat(ExeFileName, &Buf))
-    return false;  // Must not be executable!
+    return 0;                        // Must not be executable!
 
   if (!(Buf.st_mode & S_IFREG))
-    return false;                    // Not a regular file?
+    return 0;                        // Not a regular file?
 
   if (Buf.st_uid == getuid())        // Owner of file?
     return Buf.st_mode & S_IXUSR;
@@ -34,15 +35,16 @@ bool isExecutableFile(const char *ExeFileName) {
     return Buf.st_mode & S_IXOTH;
 }
 
-/// FindExecutable - Find a named executable in the directories listed in $PATH.
-/// If the executable cannot be found, returns NULL.
-/// 
+/*
+ * FindExecutable - Find a named executable in the directories listed in $PATH.
+ * If the executable cannot be found, returns NULL.
+ */ 
 char *FindExecutable(const char *ExeName) {
   /* Try to find the executable in the path */
   const char *PathStr = getenv("PATH");
   if (PathStr == 0) return "";
 
-  // Now we have a colon separated list of directories to search... try them...
+  /* Now we have a colon separated list of directories to search, try them. */
   unsigned PathLen = strlen(PathStr);
   while (PathLen) {
     /* Find the next colon */
@@ -76,6 +78,6 @@ char *FindExecutable(const char *ExeName) {
     ++Colon;
   }
 
-  // If we fell out, we ran out of directories in PATH to search, return failure
+  /* If we fell out, we ran out of directories to search, return failure. */
   return NULL;
 }

tools/llee/SysUtils.h

@@ -1,4 +1,4 @@
-/*===- sysutils.h - Utilities to do low-level system stuff -------*- C -*--===*\
+/*===- SysUtils.h - Utilities to do low-level system stuff -------*- C -*--===*\
  *                                                                            *
  * This file contains functions used to do a variety of low-level, often      *
  * system-specific, tasks.                                                    *
@@ -8,20 +8,14 @@
 #ifndef SYSUTILS_H
 #define SYSUTILS_H
 
-typedef unsigned bool;
-enum { false = 0, true = 1 };
-
 /*
  * isExecutableFile - This function returns true if the filename specified
  * exists and is executable.
  */
-bool isExecutableFile(const char *ExeFileName);
+unsigned isExecutableFile(const char *ExeFileName);
 
 /*
- * FindExecutable - Find a named executable, giving the argv[0] of program
- * being executed. This allows us to find another LLVM tool if it is built into
- * the same directory, but that directory is neither the current directory, nor
- * in the PATH.  If the executable cannot be found, return an empty string.
+ * FindExecutable - Find a named executable in the path.
  */ 
 char *FindExecutable(const char *ExeName);