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Subject[RFCv2 8/8] samples: hid: convert USI sample to use unix socket for comms
Date
Convert USI hid sample userspace interface from using unix fifo to unix
socket. This allows sending results back via the communication channel
also.

Signed-off-by: Tero Kristo <tero.kristo@linux.intel.com>
---
samples/bpf/hid_usi_user.c | 73 ++++++++++++++++++++++++++------------
1 file changed, 50 insertions(+), 23 deletions(-)

diff --git a/samples/bpf/hid_usi_user.c b/samples/bpf/hid_usi_user.c
index b05a3f768835..5bf5ebc21a30 100644
--- a/samples/bpf/hid_usi_user.c
+++ b/samples/bpf/hid_usi_user.c
@@ -14,6 +14,8 @@
#include <libgen.h>
#include <sys/resource.h>
#include <getopt.h>
+#include <sys/socket.h>
+#include <sys/un.h>

#include "bpf_util.h"
#include <bpf/bpf.h>
@@ -24,15 +26,15 @@
#include "hid_usi.h"

static char *sysfs_path;
-static char *fifoname = "/tmp/usi";
+static char *sockname = "/tmp/usi";
static int sysfs_fd;
-static int fifo_fd;
+static int sock_fd;
static int prog_count;
static int cache, wr_cache;

static const struct option long_options[] = {
{ "help", no_argument, NULL, 'h' },
- { "fifo", required_argument, NULL, 'f' },
+ { "sock", required_argument, NULL, 's' },
};

struct prog {
@@ -53,15 +55,15 @@ static void int_exit(int sig)
}

close(sysfs_fd);
- close(fifo_fd);
- remove(fifoname);
+ close(sock_fd);
+ remove(sockname);
exit(0);
}

static void usage(const char *prog)
{
fprintf(stderr,
- "usage: %s [-f <fifoname>] /dev/HIDRAW\n\n",
+ "usage: %s [-s <sockname>] /dev/HIDRAW\n\n",
prog);
}

@@ -84,15 +86,17 @@ static int write_value(const char *param, int value)

printf("%s: param=%s (%d), value=%d\n", __func__, param, idx, value);
err = bpf_map_update_elem(wr_cache, &idx, &value, BPF_ANY);
- if (err)
+ if (err) {
printf("Update failed for %d, err=%d\n", idx, err);
+ return err;
+ }

return 0;
}

static int read_value(const char *param)
{
- int value;
+ int value = -ENOENT;
int idx = param_to_idx(param);

printf("%s: param=%s (%d)\n", __func__, param, idx);
@@ -102,7 +106,7 @@ static int read_value(const char *param)
else
printf("Value for %d = %d\n", idx, value);

- return 0;
+ return value;
}

static int attach_progs(int argc, char **argv)
@@ -118,6 +122,9 @@ static int attach_progs(int argc, char **argv)
char op[8];
int value;
int m, n;
+ struct sockaddr_un addr;
+ struct sockaddr_un from;
+ socklen_t from_len = sizeof(from);

snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
obj = bpf_object__open_file(filename, NULL);
@@ -177,28 +184,48 @@ static int attach_progs(int argc, char **argv)
goto cleanup;
}

- mkfifo(fifoname, 0666);
+ sock_fd = socket(PF_UNIX, SOCK_DGRAM, 0);
+ if (sock_fd < 0) {
+ perror("socket open error.\n");
+ err = sock_fd;
+ goto cleanup;
+ }
+
+ addr.sun_family = AF_UNIX;
+ strcpy(addr.sun_path, sockname);
+ unlink(sockname);

- fifo_fd = open(fifoname, O_RDWR);
- if (fifo_fd < 0) {
- perror("Fifo open error.\n");
- err = fifo_fd;
+ if (bind(sock_fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+ perror("bind");
goto cleanup;
}

while (1) {
- n = read(fifo_fd, buf, BUFSIZ);
+ n = recvfrom(sock_fd, buf, BUFSIZ, 0, (struct sockaddr *)&from,
+ &from_len);
if (n < 0)
break;
buf[n] = 0;

printf("%s: received '%s'\n", __func__, buf);

+ printf("%s: from_len=%d, from=%s\n", __func__, from_len,
+ from.sun_path);
+
m = sscanf(buf, "%16s %8s %d", param, op, &value);
- if (m == 2 && strcmp(op, "get") == 0)
- read_value(param);
- else if (m == 3 && strcmp(op, "set") == 0)
- write_value(param, value);
+ if (m == 2 && strcmp(op, "get") == 0) {
+ value = read_value(param);
+ sprintf(buf, "%s: %d\n", param, value);
+ printf("%s: sending '%s'\n", __func__, buf);
+ sendto(sock_fd, buf, strlen(buf) + 1, 0,
+ (struct sockaddr *)&from, from_len);
+ } else if (m == 3 && strcmp(op, "set") == 0) {
+ err = write_value(param, value);
+ sprintf(buf, "%s: %d, err=%d\n", param, value, err);
+ printf("%s: sending '%s'\n", __func__, buf);
+ sendto(sock_fd, buf, strlen(buf) + 1, 0,
+ (struct sockaddr *)&from, from_len);
+ }
}

return 0;
@@ -217,11 +244,11 @@ int main(int argc, char **argv)
{
int opt;

- while ((opt = getopt_long(argc, argv, "f:", long_options,
+ while ((opt = getopt_long(argc, argv, "s:", long_options,
NULL)) != -1) {
switch (opt) {
- case 'f':
- fifoname = optarg;
+ case 's':
+ sockname = optarg;
break;
default:
usage(basename(argv[0]));
@@ -240,7 +267,7 @@ int main(int argc, char **argv)
return 1;
}

- printf("fifoname: %s\n", fifoname);
+ printf("sockname: %s\n", sockname);
printf("sysfs_path: %s\n", sysfs_path);

return attach_progs(argc, argv);
--
2.25.1
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