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-rw-r--r--src/mds.c212
1 files changed, 93 insertions, 119 deletions
diff --git a/src/mds.c b/src/mds.c
index 16d6275..c466846 100644
--- a/src/mds.c
+++ b/src/mds.c
@@ -69,9 +69,12 @@ int main(int argc_, char** argv_)
char pathname[PATH_MAX];
char piddata[64];
unsigned int display;
- FILE *f;
+ FILE* f;
int rc;
- int j;
+ int j, r;
+
+
+#define exit_if(CONDITION, INSTRUCTION) if (CONDITION) { INSTRUCTION return 1; }
argc = argc_;
@@ -79,11 +82,8 @@ int main(int argc_, char** argv_)
/* Sanity check the number of command line arguments. */
- if (argc > ARGC_LIMIT)
- {
- eprint("that number of arguments is ridiculous, I will not allow it.");
- return 1;
- }
+ exit_if (argc > ARGC_LIMIT,
+ eprint("that number of arguments is ridiculous, I will not allow it."););
/* Parse command line arguments. */
for (j = 1; j < argc; j++)
@@ -91,29 +91,20 @@ int main(int argc_, char** argv_)
char* arg = argv[j];
if (startswith(arg, "--master-server=")) /* Master server. */
{
- if (got_master_server)
- {
- eprintf("duplicate declaration of %s.", "--master-server");
- return 1;
- }
+ exit_if (got_master_server,
+ eprintf("duplicate declaration of %s.", "--master-server"););
got_master_server = 1;
master_server = arg + strlen("--master-server=");
}
}
/* Stymied if the effective user is not root. */
- if (geteuid() != ROOT_USER_UID)
- {
- eprint("the effective user is not root, cannot continue.");
- return 1;
- }
+ exit_if (geteuid() != ROOT_USER_UID,
+ eprint("the effective user is not root, cannot continue."););
/* Set up to ignore SIGUSR1, used in mds for re-exec, but we cannot re-exec. */
if (xsigaction(SIGUSR1, SIG_IGN) < 0)
- {
- perror(*argv);
- eprint("while ignoring the SIGUSR1 signal.");
- }
+ perror(*argv);
/* Create directory for socket files, PID files and such. */
if (create_directory_root(MDS_RUNTIME_ROOT_DIRECTORY))
@@ -127,88 +118,42 @@ int main(int argc_, char** argv_)
fd = open(pathname, O_CREAT | O_EXCL);
if (fd == -1)
{
- /* Reuse display index not no longer used. */
- size_t read_len;
+ /* Reuse display index if no longer used. */
f = fopen(pathname, "r");
if (f == NULL) /* Race, or error? */
{
perror(*argv);
- eprintf("while opening the file: %s", pathname);
continue;
}
- read_len = fread(piddata, 1, sizeof(piddata) / sizeof(char), f);
- if (ferror(f)) /* Failed to read. */
- {
- perror(*argv);
- eprintf("while reading the file: %s", pathname);
- }
- else if (feof(f) == 0) /* Did not read everything. */
- eprint("the content of a PID file is longer than expected.");
- else
- {
- pid_t pid = 0;
- size_t i, n = read_len - 1;
- for (i = 0; i < n; i++)
- {
- char c = piddata[i];
- if (('0' <= c) && (c <= '9'))
- pid = pid * 10 + (c & 15);
- else
- {
- eprint("the content of a PID file is invalid.");
- goto bad;
- }
- }
- if (piddata[n] != '\n')
- {
- eprint("the content of a PID file is invalid.");
- goto bad;
- }
- if (kill(pid, 0) < 0) /* Check if the PID is still allocated to any process. */
- if (errno == ESRCH) /* PID is not used. */
- {
- fclose(f);
- close(fd);
- break;
- }
- }
- bad:
+ r = is_pid_file_reusable(f);
fclose(f);
- continue;
+ if (r == 0)
+ continue;
}
close(fd);
break;
}
- if (display == DISPLAY_MAX)
- {
- eprint("sorry, too many displays on the system.");
- return 1;
- /* Yes, the directory could have been removed, but it probably was not. */
- }
+ exit_if (display == DISPLAY_MAX,
+ eprint("sorry, too many displays on the system."););
+ /* Yes, the directory could have been removed, but it probably was not. */
+
+#undef exit_if
/* Create PID file. */
- f = fopen(pathname, "w");
- if (f == NULL)
- {
- perror(*argv);
- eprintf("while opening the file: %s", pathname);
- return 1;
- }
+ if ((f = fopen(pathname, "w")) == NULL)
+ goto pfail;
xsnprintf(piddata, "%u\n", getpid());
if (fwrite(piddata, 1, strlen(piddata), f) < strlen(piddata))
{
fclose(f);
if (unlink(pathname) < 0)
perror(*argv);
- return -1;
+ return 1;
}
fflush(f);
fclose(f);
if (chmod(pathname, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) < 0)
- {
- perror(*argv);
- eprintf("while setting permissions for PID file: %s", pathname);
- }
+ perror(*argv);
/* Create data storage directory. */
if (create_directory_root(MDS_STORAGE_ROOT_DIRECTORY))
@@ -228,32 +173,13 @@ int main(int argc_, char** argv_)
strcpy(address.sun_path, pathname);
unlink(pathname);
fd = socket(AF_UNIX, SOCK_STREAM, 0);
- if (fchmod(fd, S_IRWXU) < 0)
- {
- perror(*argv);
- eprint("while making anonymous socket private to its owner.");
- goto fail;
- }
- if (bind(fd, (struct sockaddr*)(&address), sizeof(address)) < 0)
- {
- perror(*argv);
- eprintf("while binding socket to file: %s", pathname);
- goto fail;
- }
- if (chown(pathname, getuid(), NOBODY_GROUP_GID) < 0)
- {
- perror(*argv);
- eprint("while making socket private to the real user.");
- goto fail;
- }
+ if (fchmod(fd, S_IRWXU) < 0) goto pfail;
+ if (bind(fd, (struct sockaddr*)(&address), sizeof(address)) < 0) goto pfail;
+ if (chown(pathname, getuid(), NOBODY_GROUP_GID) < 0) goto pfail;
/* Start listening on socket. */
if (listen(fd, SOMAXCONN) < 0)
- {
- perror(*argv);
- eprintf("while setting up listening on socket: %s", pathname);
- goto fail;
- }
+ goto pfail;
/* Start master server and respawn it if it crashes. */
rc = spawn_and_respawn_server(fd);
@@ -279,6 +205,8 @@ int main(int argc_, char** argv_)
return rc;
+ pfail:
+ perror(*argv);
fail:
rc = 1;
goto done;
@@ -286,6 +214,64 @@ int main(int argc_, char** argv_)
/**
+ * Read a PID-file and determine whether it refers to an non-existing process
+ *
+ * @param f The PID-file
+ * @return Whether the PID-file is not longer used
+ */
+int is_pid_file_reusable(FILE* f)
+{
+ char piddata[64];
+ size_t read_len;
+
+ read_len = fread(piddata, 1, sizeof(piddata) / sizeof(char), f);
+ if (ferror(f)) /* Failed to read. */
+ perror(*argv);
+ else if (feof(f) == 0) /* Did not read everything. */
+ eprint("the content of a PID file is larger than expected.");
+ else
+ {
+ pid_t pid = parse_pid_t(piddata, read_len - 1);
+ if (pid == (pid_t)-1)
+ eprint("the content of a PID file is invalid.");
+ else
+ if (kill(pid, 0) < 0) /* Check if the PID is still allocated to any process. */
+ return errno == ESRCH; /* PID is not used. */
+ }
+
+ return 0;
+}
+
+
+/**
+ * Parse an LF-terminated string as a non-negative `pid_t`
+ *
+ * @param str The string
+ * @param n The length of the string, excluding LF-termination
+ * @return The pid, `(pid_t)-1` if malformated
+ */
+pid_t parse_pid_t(const char* str, size_t n)
+{
+ pid_t pid = 0;
+ size_t i;
+
+ for (i = 0; i < n; i++)
+ {
+ char c = str[i];
+ if (('0' <= c) && (c <= '9'))
+ pid = pid * 10 + (c & 15);
+ else
+ return (pid_t)-1;
+ }
+
+ if (str[n] != '\n')
+ return (pid_t)-1;
+
+ return pid;
+}
+
+
+/**
* Start master server and respawn it if it crashes
*
* @param fd The file descriptor of the socket
@@ -322,7 +308,6 @@ int spawn_and_respawn_server(int fd)
if (pid == (pid_t)-1)
{
perror(*argv);
- eprint("while forking.");
goto fail;
}
@@ -331,16 +316,12 @@ int spawn_and_respawn_server(int fd)
/* Get the current time. (Start of child process.) */
time_error = (monotone(&time_start) < 0);
if (time_error)
- {
- perror(*argv);
- eprint("while reading a monotonic clock.");
- }
+ perror(*argv);
/* Wait for master server to die. */
if (waitpid(pid, &status, 0) == (pid_t)-1)
{
perror(*argv);
- eprint("while waiting for child process to exit.");
goto fail;
}
@@ -376,7 +357,6 @@ int spawn_and_respawn_server(int fd)
if (child_args[argc + 0] == NULL)
{
perror(*argv);
- eprint("while duplicating string.");
goto fail;
}
}
@@ -389,14 +369,12 @@ int spawn_and_respawn_server(int fd)
if (drop_privileges())
{
perror(*argv);
- eprint("while dropping privileges.");
goto fail;
}
/* Start master server. */
execv(master_server, child_args);
perror(*argv);
- eprint("while changing execution image.");
goto fail;
}
}
@@ -440,7 +418,6 @@ int create_directory_root(const char* pathname)
if (errno != EEXIST) /* Unlikely race condition. */
{
perror(*argv);
- eprintf("while creating directory: %s", pathname);
return 1;
}
}
@@ -449,7 +426,6 @@ int create_directory_root(const char* pathname)
if (chown(pathname, ROOT_USER_UID, ROOT_GROUP_GID) < 0)
{
perror(*argv);
- eprintf("while changing owner of directory: %s", pathname);
return 1;
}
}
@@ -486,7 +462,6 @@ int create_directory_user(const char* pathname)
if (errno != EEXIST) /* Unlikely race condition. */
{
perror(*argv);
- eprintf("while creating directory: %s", pathname);
return 1;
}
}
@@ -495,7 +470,6 @@ int create_directory_user(const char* pathname)
if (chown(pathname, getuid(), NOBODY_GROUP_GID) < 0)
{
perror(*argv);
- eprintf("while changing owner of directory: %s", pathname);
return 1;
}
}
@@ -516,6 +490,7 @@ int unlink_recursive(const char* pathname)
int rc = 0;
struct dirent* file;
+ /* Check that we could examine the directory. */
if (dir == NULL)
{
int errno_ = errno;
@@ -524,10 +499,10 @@ int unlink_recursive(const char* pathname)
return 0;
errno = errno_;
perror(*argv);
- eprintf("while examining the content of directory: %s", pathname);
return 1;
}
+ /* Remove the content of the directory. */
while ((file = readdir(dir)) != NULL)
if (strcmp(file->d_name, ".") && strcmp(file->d_name, ".."))
if (unlink(file->d_name) < 0)
@@ -537,17 +512,16 @@ int unlink_recursive(const char* pathname)
else
{
perror(*argv);
- eprintf("while unlinking file: %s", file->d_name);
rc = 1;
goto done;
}
eprint("pop");
}
+ /* Remvoe the drectory. */
if (rmdir(pathname) < 0)
{
perror(*argv);
- eprintf("while removing directory: %s", pathname);
rc = 1;
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-13 02:37:44 +0000