Make evemu ABI resilient

Hide the evemu struct, make it versioned, and instead use new/delete
and accessor functions. This should give us enough ABI stability to
run mixed library implementations.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

6 files changed, 107 insertions, 48 deletions

diff --git a/include/evemu.h b/include/evemu.h
index 70a5bd5..698a539 100644
--- a/include/evemu.h
+++ b/include/evemu.h
@@ -26,28 +26,22 @@
  *
  ****************************************************************************/
 
-#ifndef _EVPLAY_H
-#define _EVPLAY_H
+#ifndef _EVEMU_H
+#define _EVEMU_H
 
-#include <linux/uinput.h>
 #include <stdio.h>
+#include <errno.h>
+#include <linux/input.h>
 
-#define EVPLAY_NBITS    KEY_CNT
-#define EVPLAY_NBYTES   ((EVPLAY_NBITS + 7) / 8)
+#define EVEMU_VERSION_MAJOR     1
+#define EVEMU_VERSION_MINOR     1
 
-struct evemu_device {
-        char name[UINPUT_MAX_NAME_SIZE];
-        struct input_id id;
-        unsigned char mask[EV_CNT][EVPLAY_NBYTES];
-        int bytes[EV_CNT];
-        struct input_absinfo abs[ABS_CNT];
-};
+struct evemu_device *evemu_new(const char *name);
+void evemu_delete(struct evemu_device *dev);
 
-static inline int evemu_has(const struct evemu_device *dev,
-                             int type, int code)
-{
-        return (dev->mask[type][code >> 3] >> (code & 7)) & 1;
-}
+const char *evemu_get_name(const struct evemu_device *dev);
+
+int evemu_has(const struct evemu_device *dev, int type, int code);
 
 int evemu_extract(struct evemu_device *dev, int fd);
 int evemu_write(const struct evemu_device *dev, FILE *fp);
diff --git a/src/evemu-impl.h b/src/evemu-impl.h
new file mode 100644
index 0000000..2346590
--- /dev/null
+++ b/src/evemu-impl.h
@@ -0,0 +1,19 @@
+#ifndef _EVEMU_IMPL_H
+#define _EVEMU_IMPL_H
+
+#include <evemu.h>
+#include <linux/uinput.h>
+
+#define EVPLAY_NBITS    KEY_CNT
+#define EVPLAY_NBYTES   ((EVPLAY_NBITS + 7) / 8)
+
+struct evemu_device {
+        int version_major, version_minor;
+        char name[UINPUT_MAX_NAME_SIZE];
+        struct input_id id;
+        unsigned char mask[EV_CNT][EVPLAY_NBYTES];
+        int bytes[EV_CNT];
+        struct input_absinfo abs[ABS_CNT];
+};
+
+#endif
diff --git a/src/evemu.c b/src/evemu.c
index 54156aa..53bda86 100644
--- a/src/evemu.c
+++ b/src/evemu.c
@@ -26,7 +26,8 @@
  *
  ****************************************************************************/
 
-#include "evemu.h"
+#include "evemu-impl.h"
+#include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include <fcntl.h>
@@ -44,6 +45,34 @@ static void copy_bits(unsigned char *mask, const unsigned long *bits, int bytes)
         }
 }
 
+struct evemu_device *evemu_new(const char *name)
+{
+        struct evemu_device *dev = calloc(1, sizeof(struct evemu_device));
+
+        dev->version_major = EVEMU_VERSION_MAJOR;
+        dev->version_minor = EVEMU_VERSION_MINOR;
+
+        if (name && strlen(name) < sizeof(dev->name))
+                strcpy(dev->name, name);
+
+        return dev;
+}
+
+void evemu_delete(struct evemu_device *dev)
+{
+        free(dev);
+}
+
+const char *evemu_get_name(const struct evemu_device *dev)
+{
+        return dev->name;
+}
+
+int evemu_has(const struct evemu_device *dev, int type, int code)
+{
+        return (dev->mask[type][code >> 3] >> (code & 7)) & 1;
+}
+
 int evemu_extract(struct evemu_device *dev, int fd)
 {
         unsigned long bits[64];
diff --git a/tools/evemu-describe.c b/tools/evemu-describe.c
index ec6b1ef..6c6cdab 100644
--- a/tools/evemu-describe.c
+++ b/tools/evemu-describe.c
@@ -26,22 +26,27 @@
  *
  ****************************************************************************/
 
-#include "evemu.h"
+#include <evemu.h>
 #include <stdio.h>
 #include <fcntl.h>
 #include <string.h>
 
 static int describe_device(int fd)
 {
-        struct evemu_device dev;
-        int ret;
+        struct evemu_device *dev;
+        int ret = -ENOMEM;
 
-        ret = evemu_extract(&dev, fd);
+        dev = evemu_new(0);
+        if (!dev)
+                goto out;
+        ret = evemu_extract(dev, fd);
         if (ret)
-                return ret;
-        evemu_write(&dev, stdout);
+                goto out;
 
-        return 0;
+        evemu_write(dev, stdout);
+out:
+        evemu_delete(dev);
+        return ret;
 }
 
 int main(int argc, char *argv[])
diff --git a/tools/evemu-device.c b/tools/evemu-device.c
index b318cf6..79193ff 100644
--- a/tools/evemu-device.c
+++ b/tools/evemu-device.c
@@ -50,7 +50,7 @@ static void hold_device(const struct evemu_device *dev)
                 ret = read(fd, name, sizeof(name));
                 if (ret > 0)
                         name[ret - 1] = 0;
-                if (!strcmp(dev->name, name))
+                if (!strcmp(evemu_get_name(dev), name))
                         sprintf(node, "/dev/input/event%d", i + 1);
                 close(fd);
         }
@@ -58,7 +58,7 @@ static void hold_device(const struct evemu_device *dev)
         fd = open(node, O_RDONLY);
         if (fd < 0)
                 return;
-        fprintf(stdout, "%s: %s\n", dev->name, node);
+        fprintf(stdout, "%s: %s\n", evemu_get_name(dev), node);
         fflush(stdout);
         while ((ret = read(fd, data, sizeof(data))) > 0);
         close(fd);
@@ -66,28 +66,36 @@ static void hold_device(const struct evemu_device *dev)
 
 static int evemu_device(FILE *fp)
 {
-        struct evemu_device dev;
-        int ret, fd;
+        struct evemu_device *dev;
+        char name[64];
+        int ret = -ENOMEM;
+        int fd;
 
-        ret = evemu_read(&dev, fp);
-        if (ret <= 0)
-                return ret;
+        sprintf(name, "evemu-%d", getpid());
 
-        sprintf(dev.name, "evemu-%d", getpid());
+        dev = evemu_new(name);
+        if (!dev)
+                goto out;
+        ret = evemu_read(dev, fp);
+        if (ret <= 0)
+                goto out;
 
-        fd = open(UINPUT_NODE, O_WRONLY);
-        if (fd < 0)
-                return fd;
-        ret = evemu_create(&dev, fd);
+        ret = fd = open(UINPUT_NODE, O_WRONLY);
         if (ret < 0)
-                return ret;
-
-        hold_device(&dev);
+                goto out;
 
+        ret = evemu_create(dev, fd);
+        if (ret < 0)
+                goto out_close;
+        hold_device(dev);
         evemu_destroy(fd);
+
+out_close:
         close(fd);
+out:
+        evemu_delete(dev);
 
-        return 0;
+        return ret;
 }
 
 int main(int argc, char *argv[])
diff --git a/tools/evemu-echo.c b/tools/evemu-echo.c
index d3501ea..e9c89df 100644
--- a/tools/evemu-echo.c
+++ b/tools/evemu-echo.c
@@ -33,16 +33,20 @@
 
 static int evemu_echo_describe(FILE *fp)
 {
-        struct evemu_device dev;
-        int ret;
+        struct evemu_device *dev;
+        int ret = -ENOMEM;
 
-        ret = evemu_read(&dev, fp);
+        dev = evemu_new(0);
+        if (!dev)
+                goto out;
+        ret = evemu_read(dev, fp);
         if (ret <= 0)
-                return ret;
-
-        evemu_write(&dev, stdout);
+                goto out;
 
-        return 0;
+        evemu_write(dev, stdout);
+out:
+        evemu_delete(dev);
+        return ret;
 }
 
 static int evemu_echo_event(FILE *fp)