Make state, runtime and dev paths configurable at runtime

src/auth.c

@@ -41,6 +41,7 @@
 
 #include "config.h"
 #include "auth.h"
+#include "common.h"
 #include "dhcp.h"
 #include "dhcp6.h"
 #include "dhcpcd.h"
@@ -437,16 +438,17 @@ auth_get_rdm_monotonic(uint64_t *rdm)
 	int flocked;
 #endif
 
-	fp = fopen(RDM_MONOFILE, "r+");
+	ensure_dir(dhcpcd_rdm_monofile, 0750);
+	fp = fopen(dhcpcd_rdm_monofile, "r+");
 	if (fp == NULL) {
 		if (errno != ENOENT)
 			return -1;
-		fp = fopen(RDM_MONOFILE, "w");
+		fp = fopen(dhcpcd_rdm_monofile, "w");
 		if (fp == NULL)
 			return -1;
-		if (chmod(RDM_MONOFILE, 0400) == -1) {
+		if (chmod(dhcpcd_rdm_monofile, 0400) == -1) {
 			(void)fclose(fp);
-			unlink(RDM_MONOFILE);
+			unlink(dhcpcd_rdm_monofile);
 			return -1;
 		}
 #ifdef LOCK_EX

src/common.c

@@ -146,12 +146,96 @@ readfile(const char *file, void **data, size_t *len)
 	return bytes;
 }
 
+/* Return a copy of s with every '%' doubled so it is safe to use as a
+ * literal within a printf-style format string. Returns NULL on failure. */
+char *
+escape_percent(const char *s)
+{
+	const char *p;
+	char *r, *d;
+	size_t extra = 0;
+
+	if (s == NULL)
+		s = "";
+	for (p = s; *p != '\0'; p++)
+		if (*p == '%')
+			extra++;
+	r = malloc(strlen(s) + extra + 1);
+	if (r == NULL)
+		return NULL;
+	for (p = s, d = r; *p != '\0'; p++) {
+		if (*p == '%')
+			*d++ = '%';
+		*d++ = *p;
+	}
+	*d = '\0';
+	return r;
+}
+
+/* Create a directory and any missing parents, like mkdir -p. */
+int
+mkdirs(const char *dir, mode_t mode)
+{
+	char *d, *p;
+	int r = 0;
+
+	if (dir == NULL || dir[0] == '\0') {
+		errno = EINVAL;
+		return -1;
+	}
+	d = strdup(dir);
+	if (d == NULL)
+		return -1;
+	for (p = d + 1; *p != '\0'; p++) {
+		if (*p != '/')
+			continue;
+		*p = '\0';
+		if (mkdir(d, mode) == -1 && errno != EEXIST)
+			r = -1;
+		*p = '/';
+	}
+	if (mkdir(d, mode) == -1 && errno != EEXIST)
+		r = -1;
+	free(d);
+	return r;
+}
+
+/* Ensure the directory part of a file path exists. */
+int
+ensure_dir(const char *file, mode_t mode)
+{
+	char *d, *p;
+	int r;
+
+	if (file == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	d = strdup(file);
+	if (d == NULL)
+		return -1;
+	p = strrchr(d, '/');
+	if (p == NULL) {
+		free(d);
+		return 0;
+	}
+	if (p == d)
+		*(p + 1) = '\0';
+	else
+		*p = '\0';
+	r = mkdirs(d, mode);
+	free(d);
+	return r;
+}
+
 ssize_t
 writefile(const char *file, mode_t mode, const void *data, size_t len)
 {
 	int fd;
 	ssize_t bytes;
 
+	if (ensure_dir(file, 0750) == -1)
+		return -1;
 	fd = open(file, O_WRONLY | O_CREAT | O_TRUNC, mode);
 	if (fd == -1)
 		return -1;

src/common.h

@@ -169,6 +169,9 @@ const char *hwaddr_ntoa(const void *, size_t, char *, size_t);
 size_t hwaddr_aton(uint8_t *, const char *);
 ssize_t readfile(const char *, void **, size_t *);
 ssize_t writefile(const char *, mode_t, const void *, size_t);
+char *escape_percent(const char *);
+int mkdirs(const char *, mode_t);
+int ensure_dir(const char *, mode_t);
 int filemtime(const char *, time_t *);
 char *get_line(char **__restrict, size_t *__restrict);
 int is_root_local(void);

src/control.c

@@ -491,7 +491,7 @@ make_path(char *path, size_t len, const char *ifname, sa_family_t family)
 		per = "";
 		break;
 	}
-	return snprintf(path, len, CONTROLSOCKET, ifname ? ifname : "",
+	return snprintf(path, len, dhcpcd_controlsock, ifname ? ifname : "",
 	    ifname ? per : "", "", ifname ? "." : "");
 }
 
@@ -521,6 +521,8 @@ control_start1(struct dhcpcd_ctx *ctx, const char *ifname, sa_family_t family)
 	if (fd == -1)
 		return -1;
 
+	ensure_dir(sa.sun_path, 0755);
+
 	len = (socklen_t)SUN_LEN(&sa);
 	if (GID_SET(ctx->control_group) && GID_SET(ctx->read_group)) {
 		if (ctx->control_group == ctx->read_group) {

src/defs.h

@@ -66,6 +66,32 @@
 #define RDM_MONOFILE DBDIR "/rdm_monotonic"
 #endif
 
+/*
+ * Runtime configurable paths.
+ * These default to the compiled in values but can be overridden at runtime
+ * with the corresponding command line options (--instance, --dbdir, --rundir,
+ * --devdir). The individual file paths are derived from these and rebuilt
+ * whenever a base directory is changed (see dhcpcd_paths_update()).
+ */
+extern const char *dhcpcd_dbdir;
+extern const char *dhcpcd_rundir;
+extern const char *dhcpcd_devdir;
+extern const char *dhcpcd_instance;
+extern const char *dhcpcd_duidfile;
+extern const char *dhcpcd_secretfile;
+extern const char *dhcpcd_rdm_monofile;
+extern const char *dhcpcd_leasefile;
+extern const char *dhcpcd_leasefile6;
+extern const char *dhcpcd_pidfile;
+extern const char *dhcpcd_controlsock;
+
+void dhcpcd_paths_init(void);
+void dhcpcd_paths_update(void);
+void dhcpcd_paths_set_dbdir(const char *);
+void dhcpcd_paths_set_rundir(const char *);
+void dhcpcd_paths_set_devdir(const char *);
+void dhcpcd_paths_set_instance(const char *);
+
 #ifndef NO_SIGNALS
 #define USE_SIGNALS
 #endif

src/dev.c

@@ -99,7 +99,7 @@ dev_start2(struct dhcpcd_ctx *ctx, const struct dev_dhcpcd *dev_dhcpcd,
 	void (*fptr)(struct dev *, const struct dev_dhcpcd *);
 	int r;
 
-	snprintf(file, sizeof(file), DEVDIR "/%s", name);
+	snprintf(file, sizeof(file), "%s/%s", dhcpcd_devdir, name);
 	h = dlopen(file, RTLD_LAZY);
 	if (h == NULL) {
 		logerrx("dlopen: %s", dlerror());
@@ -143,9 +143,9 @@ dev_start1(struct dhcpcd_ctx *ctx, const struct dev_dhcpcd *dev_dhcpcd)
 	if (ctx->dev_load)
 		return dev_start2(ctx, dev_dhcpcd, ctx->dev_load);
 
-	dp = opendir(DEVDIR);
+	dp = opendir(dhcpcd_devdir);
 	if (dp == NULL) {
-		logdebug("dev: %s", DEVDIR);
+		logdebug("dev: %s", dhcpcd_devdir);
 		return -1;
 	}
 

src/dhcp-common.c

@@ -1041,7 +1041,8 @@ dhcp_set_leasefile(char *leasefile, size_t len, int family,
 	} else
 		ssid[0] = '\0';
 	return snprintf(leasefile, len,
-	    family == AF_INET ? LEASEFILE : LEASEFILE6, ifname, ssid);
+	    family == AF_INET ? dhcpcd_leasefile : dhcpcd_leasefile6, ifname,
+	    ssid);
 }
 
 void

src/dhcpcd.8.in

@@ -61,6 +61,10 @@
 .Op Fl Z , Fl Fl denyinterfaces Ar pattern
 .Op Fl z , Fl Fl allowinterfaces Ar pattern
 .Op Fl Fl inactive
+.Op Fl Fl instance Ar instance
+.Op Fl Fl dbdir Ar dir
+.Op Fl Fl rundir Ar dir
+.Op Fl Fl devdir Ar dir
 .Op Fl Fl configure
 .Op Fl Fl noconfigure
 .Op interface
@@ -271,9 +275,9 @@ Use a DHCP Unique Identifier.
 If persistent storage is available then a DUID-LLT
 (link local address + time) is generated,
 otherwise DUID-LL is generated (link local address).
-The DUID type can be hinted as an optional parameter if the file
-.Pa @DBDIR@/duid
-does not exist.
+ The DUID type can be hinted as an optional parameter if the default DUID file
+ .Pa @DBDIR@/duid
+ does not exist.
 If not
 .Va ll ,
 .Va lt
@@ -284,9 +288,9 @@ then
 will be converted from 00:11:22:33 format.
 This, plus the IAID will be used as the
 .Fl I , Fl Fl clientid .
-The DUID generated will be held in
-.Pa @DBDIR@/duid
-and should not be copied to other hosts.
+ The DUID generated will be held in the default DUID file
+ .Pa @DBDIR@/duid
+ and should not be copied to other hosts.
 This file also takes precedence over the above rules except for setting a value.
 .It Fl d , Fl Fl debug
 Echo debug messages to the stderr and syslog.
@@ -778,6 +782,51 @@ addition of
 Don't load any
 .Pa /dev
 management modules.
+.It Fl Fl instance Ar instance
+Prefix the state and runtime files that
+.Nm
+writes, namely the DUID, secret, lease, RDM, PID and control socket files,
+with the
+.Ar instance
+name inside the state and runtime directories.
+.Ar instance
+must be a single path component and must not contain a
+.Sq / .
+For example,
+.Fl Fl instance=foo
+will cause the DUID file to be written to
+.Pa @DBDIR@/ Ns Pa foo Ns .duid
+and the PID file to
+.Pa @RUNDIR@/ Ns Pa foo Ns .pid .
+The base directories remain unchanged.
+.It Fl Fl dbdir Ar dir
+Specify the base directory where
+.Nm
+stores its lease and state database.
+This overrides the compiled in default
+.Pa @DBDIR@ .
+Without
+.Fl Fl instance
+the DUID, secret, lease and RDM files are created directly here, otherwise
+they are created here under the file name prefixed with the instance name.
+.It Fl Fl rundir Ar dir
+Specify the base directory where
+.Nm
+stores its runtime files, such as the PID file and control socket.
+This overrides the compiled in default
+.Pa @RUNDIR@ .
+Without
+.Fl Fl instance
+the PID file and control socket are created directly here, otherwise they
+are created here under the file name prefixed with the instance name.
+.It Fl Fl devdir Ar dir
+Specify the directory from which
+.Nm
+loads
+.Pa /dev
+management modules.
+This overrides the compiled in default
+.Pa @LIBDIR@/dhcpcd/dev .
 .El
 .Sh 3RDPARTY LINK MANAGEMENT
 Some interfaces require configuration by 3rd parties, such as PPP or VPN.
@@ -818,6 +867,18 @@ sends to match.
 If using a DUID in place of the ClientID, edit
 .Pa @DBDIR@/duid
 accordingly.
+.Pp
+The file paths shown in this manual, such as
+.Pa @DBDIR@/duid ,
+are the compiled in defaults.
+The effective path used by
+.Nm
+can be changed with the
+.Fl Fl dbdir ,
+.Fl Fl rundir
+and
+.Fl Fl instance
+options described above.
 .Sh FILES
 .Bl -ohang
 .It Pa @SYSCONFDIR@/dhcpcd.conf