I've written a C application that grabs some sensor data and puts it into a string. This string gets passed to gammu-smsd-inject for transmission by SMSD. For reference, my application launches gammu-smsd-inject using fork() & wait(). The program waits for gammu-smsd-inject to terminate and then exits itself.
My program works just fine: if I run it manually from a bash prompt it grabs the sensor data, calls gammu-smsd-inject and quits. The sms appears in the database outbox and shortly after I receive an sms on my phone.
I've added the absolute path to my program into the runonreceive directive of SMSD. When I send a text to SMSD, it is received in the inbox and from the log file I can see the daemon running my program. The logfile then states that the process (my program) successfully exited (0), but I never receive any sms and nothing is added to the database's outbox or sentitems tables.
Any idea what might be going on? I haven't posted a code listing as it's quite long,but it is available.
The only think I could think of that might be happening is that gammu-smsd-inject is perhaps being terminated (by a parent process somewhere up the tree) BEFORE it gets a chance to do any SQL stuff. Wouldn't this create a non zero exit code though?
So the problem was which user was running the program. When I ran my application manually from bash, it launch it with my user ID, but when the SMSD daemon ran it, it was launched with a different ID which was causing issues for some reason. I thought it was a problem with the user ID being used to access the mysql database, but apparently not. In short, I don't actually know what the problem was, but by assigning my login's UID to the child process, everything suddenly worked.