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593ece0050
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
103 lines
3.2 KiB
C
103 lines
3.2 KiB
C
//===-- ExecveHandler.c - Replaces execve() to run LLVM files -------------===//
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//
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// This file implements a replacement execve() to spawn off LLVM programs to run
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// transparently, without needing to be (JIT-)compiled manually by the user.
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//
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//===----------------------------------------------------------------------===//
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#include "SysUtils.h"
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#include "Config/dlfcn.h"
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#include "Config/errno.h"
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#include "Config/stdlib.h"
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#include "Config/unistd.h"
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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/*
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* This is the expected header for all valid LLVM bytecode files.
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* The first four characters must be exactly this.
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*/
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static const char llvmHeader[] = "llvm";
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/*
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* The type of the execve() function is long and boring, but required.
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*/
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typedef int(*execveTy)(const char*, char *const[], char *const[]);
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/*
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* This method finds the real `execve' call in the C library and executes the
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* given program.
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*/
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int executeProgram(const char *filename, char *const argv[], char *const envp[])
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{
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/*
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* Find a pointer to the *real* execve() function starting the search in the
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* next library and forward, to avoid finding the one defined in this file.
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*/
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char *error;
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execveTy execvePtr = (execveTy) dlsym(RTLD_NEXT, "execve");
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if ((error = dlerror()) != NULL) {
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fprintf(stderr, "%s\n", error);
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return -1;
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}
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/* Really execute the program */
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return execvePtr(filename, argv, envp);
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}
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/*
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* This replacement execve() function first checks the file to be executed
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* to see if it is a valid LLVM bytecode file, and then either invokes our
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* execution environment or passes it on to the system execve() call.
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*/
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int execve(const char *filename, char *const argv[], char *const envp[])
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{
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/* Open the file, test to see if first four characters are "llvm" */
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size_t headerSize = strlen(llvmHeader);
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char header[headerSize];
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errno = 0;
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int file = open(filename, O_RDONLY);
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/* Check validity of `file' */
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if (errno) return EIO;
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/* Read the header from the file */
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ssize_t bytesRead = read(file, header, headerSize);
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close(file);
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if (bytesRead != headerSize) return EIO;
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if (!memcmp(llvmHeader, header, headerSize)) {
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/*
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* This is a bytecode file, so execute the JIT with the program and
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* parameters.
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*/
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unsigned argvSize, idx;
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for (argvSize = 0, idx = 0; argv[idx] && argv[idx][0]; ++idx)
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++argvSize;
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char **LLIargs = (char**) malloc(sizeof(char*) * (argvSize+2));
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char *BCpath;
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/*
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* If the program is specified with a relative or absolute path,
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* then just use the path and filename as is, otherwise search for it.
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*/
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if (filename[0] != '.' && filename[0] != '/')
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BCpath = FindExecutable(filename);
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else
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BCpath = (char*) filename;
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if (!BCpath) {
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fprintf(stderr, "Cannot find path to `%s', exiting.\n", filename);
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return -1;
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}
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char *LLIpath = FindExecutable("lli");
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if (!LLIpath) {
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fprintf(stderr, "Cannot find path to `lli', exiting.\n");
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return -1;
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}
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LLIargs[0] = LLIpath;
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LLIargs[1] = BCpath;
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for (idx = 1; idx != argvSize; ++idx)
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LLIargs[idx+1] = argv[idx];
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LLIargs[argvSize + 1] = '\0';
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return executeProgram(LLIpath, LLIargs, envp);
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}
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return executeProgram(filename, argv, envp);
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}
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