diff options
Diffstat (limited to 'tools/libxl/libxl_exec.c')
| -rw-r--r-- | tools/libxl/libxl_exec.c | 189 |
1 files changed, 173 insertions, 16 deletions
diff --git a/tools/libxl/libxl_exec.c b/tools/libxl/libxl_exec.c index 5186ac8c7c..de79b64e73 100644 --- a/tools/libxl/libxl_exec.c +++ b/tools/libxl/libxl_exec.c @@ -18,34 +18,191 @@ #include "libxl_osdeps.h" #include <stdio.h> +#include <string.h> #include <unistd.h> #include <stdlib.h> +#include <unistd.h> +#include <assert.h> +#include <sys/types.h> +#include <sys/wait.h> #include "libxl.h" #include "libxl_internal.h" -int libxl_exec(struct libxl_ctx *ctx, int stdinfd, int stdoutfd, int stderrfd, - char *arg0, char **args) +pid_t libxl_fork(struct libxl_ctx *ctx) { - int pid, i; + pid_t pid; pid = fork(); if (pid == -1) { XL_LOG_ERRNO(ctx, XL_LOG_ERROR, "fork failed"); return -1; } - if (pid == 0) { - /* child */ - if (stdinfd != -1) - dup2(stdinfd, STDIN_FILENO); - if (stdoutfd != -1) - dup2(stdoutfd, STDOUT_FILENO); - if (stderrfd != -1) - dup2(stderrfd, STDERR_FILENO); - for (i = 4; i < 256; i++) - close(i); - execv(arg0, args); - exit(256); - } + return pid; } + +void libxl_exec(struct libxl_ctx *ctx, int stdinfd, int stdoutfd, int stderrfd, + char *arg0, char **args) + /* call this in the child */ +{ + int i; + + if (stdinfd != -1) + dup2(stdinfd, STDIN_FILENO); + if (stdoutfd != -1) + dup2(stdoutfd, STDOUT_FILENO); + if (stderrfd != -1) + dup2(stderrfd, STDERR_FILENO); + for (i = 4; i < 256; i++) + close(i); + execv(arg0, args); + XL_LOG_ERRNO(ctx, XL_LOG_ERROR, "exec %s failed", arg0); + _exit(-1); +} + +void libxl_report_child_exitstatus(struct libxl_ctx *ctx, + const char *what, pid_t pid, int status) { + /* treats all exit statuses as errors; if that's not what you want, + * check status yourself first */ + + if (WIFEXITED(status)) { + int st= WEXITSTATUS(status); + if (st) + XL_LOG(ctx, XL_LOG_ERROR, "%s [%ld] exited" + " with error status %d", what, (unsigned long)pid, st); + else + XL_LOG(ctx, XL_LOG_ERROR, "%s [%ld] unexpectedly" + " exited status zero", what, (unsigned long)pid); + } else if (WIFSIGNALED(status)) { + int sig= WTERMSIG(status); + const char *str= strsignal(sig); + const char *coredump= WCOREDUMP(status) ? " (core dumped)" : ""; + if (str) + XL_LOG(ctx, XL_LOG_ERROR, "%s [%ld] died due to" + " fatal signal %s%s", what, (unsigned long)pid, + str, coredump); + else + XL_LOG(ctx, XL_LOG_ERROR, "%s [%ld] died due to unknown" + " fatal signal number %d%s", what, (unsigned long)pid, + sig, coredump); + } else { + XL_LOG(ctx, XL_LOG_ERROR, "%s [%ld] gave unknown" + " wait status 0x%x", what, (unsigned long)pid, status); + } +} + +pid_t libxl_waitpid_instead_default(pid_t pid, int *status, int flags) { + return waitpid(pid,status,flags); +} + + + +int libxl_spawn_spawn(struct libxl_ctx *ctx, + struct libxl_spawn_starting *for_spawn, + const char *what, + void (*intermediate_hook)(struct libxl_ctx *ctx, + void *for_spawn, + pid_t innerchild)) { + pid_t child, got; + int status; + pid_t intermediate; + + if (for_spawn) { + for_spawn->what= strdup(what); + if (!for_spawn->what) return ERROR_NOMEM; + } + + intermediate = libxl_fork(ctx); + if (intermediate==-1) { + if (for_spawn) free(for_spawn->what); + return ERROR_FAIL; + } + if (intermediate) { + /* parent */ + if (for_spawn) for_spawn->intermediate= intermediate; + return 1; + } + + /* we are now the intermediate process */ + + child = libxl_fork(ctx); + if (!child) return 0; /* caller runs child code */ + if (child<0) exit(255); + + intermediate_hook(ctx, for_spawn, child); + + if (!for_spawn) _exit(0); /* just detach then */ + + got = ctx->waitpid_instead(child, &status, 0); + assert(got == child); + + libxl_report_child_exitstatus(ctx, what, child, status); + _exit(WIFEXITED(status) ? WEXITSTATUS(status) : + WIFSIGNALED(status) && WTERMSIG(status)<127 + ? WTERMSIG(status)+128 : -1); +} + +static void report_spawn_intermediate_status(struct libxl_ctx *ctx, + struct libxl_spawn_starting *for_spawn, + int status) { + if (!WIFEXITED(status)) { + /* intermediate process did the logging itself if it exited */ + char *intermediate_what= + libxl_sprintf(ctx, + "%s intermediate process (startup monitor)", + for_spawn->what); + libxl_report_child_exitstatus(ctx, intermediate_what, + for_spawn->intermediate, status); + } +} + +int libxl_spawn_detach(struct libxl_ctx *ctx, + struct libxl_spawn_starting *for_spawn) { + int r, status; + pid_t got; + int rc = 0; + + if (!for_spawn) return 0; + + if (for_spawn->intermediate) { + r = kill(for_spawn->intermediate, SIGKILL); + if (r) { + XL_LOG_ERRNO(ctx, XL_LOG_ERROR, + "could not kill %s intermediate process [%ld]", + for_spawn->what, + (unsigned long)for_spawn->intermediate); + abort(); /* things are very wrong */ + } + got = ctx->waitpid_instead(for_spawn->intermediate, &status, 0); + assert(got == for_spawn->intermediate); + if (!(WIFSIGNALED(status) && WTERMSIG(status)==SIGKILL)) { + report_spawn_intermediate_status(ctx, for_spawn, status); + rc = ERROR_FAIL; + } + for_spawn->intermediate = 0; + } + + free(for_spawn->what); + for_spawn->what = 0; + + return rc; +} + +int libxl_spawn_check(struct libxl_ctx *ctx, void *for_spawn_void) { + struct libxl_spawn_starting *for_spawn = for_spawn_void; + pid_t got; + int status; + + if (!for_spawn) return 0; + + assert(for_spawn->intermediate); + got = ctx->waitpid_instead(for_spawn->intermediate, &status, WNOHANG); + if (!got) return 0; + + assert(got == for_spawn->intermediate); + report_spawn_intermediate_status(ctx, for_spawn, status); + + for_spawn->intermediate= 0; + return ERROR_FAIL; +} |