ipc-sockets

src/include/errno.h

@@ -0,0 +1,88 @@
+/*
+ * lux - a lightweight unix-like operating system
+ * Omar Elghoul, 2024
+ * 
+ * Core Microkernel
+ */
+
+#pragma once
+
+/* System Error Numbers */
+
+#define E2BIG               1   // too many args
+#define EACCES              2   // access denied
+#define EADDRINUSE          3   // address in use
+#define EADDRNOTAVAIL       4   // address not available
+#define EAFNOSUPPORT        5   // address family not supported
+#define EAGAIN              6   // resource busy, try again
+#define EALREADY            7   // connection already in progress
+#define EBADF               8   // bad file descriptor
+#define EBADMSG             9   // bad message
+#define EBUSY               10  // resource busy
+#define ECANCELED           11  // canceled
+#define ECHILD              12  // no child processes
+#define ECONNABORTED        13  // connection aborted
+#define ECONNREFUSED        14  // connection refused
+#define ECONNRESET          15  // connection reset
+#define EDEADLK             16  // deadlock
+#define EDESTADDRREQ        17  // destination address required
+#define EDOM                18  // function argument not in domain
+#define EDQUOT              19  // reserved
+#define EEXIST              20  // file exists
+#define EFAULT              21  // bad address
+#define EFBIG               22  // file too big
+#define EHOSTUNREACH        23  // host unreachable
+#define EIDRM               24  // identifier removed
+#define EILSEQ              25  // illegal byte sequence
+#define EINPROGRESS         26  // operation in progress
+#define EINTR               27  // interrupted function
+#define EINVAL              28  // invalid argument
+#define EIO                 29  // I/O error
+#define EISCONN             30  // socket already connected
+#define EISDIR              31  // directory
+#define ELOOP               32  // looping symlinks
+#define EMFILE              33  // file descriptor too big
+#define EMLINK              34  // too many links
+#define EMSGSIZE            35  // message too large
+#define EMULTIHOP           36  // reserved
+#define ENAMETOOLONG        37  // file name too long
+#define ENETDOWN            38  // network is down
+#define ENETRESET           39  // connection aborted by network
+#define ENETUNREACH         40  // network unreachable
+#define ENFILE              41  // too many files open
+#define ENOBUFS             42  // no buffers available
+#define ENODEV              43  // no such device
+#define ENOENT              44  // no such file/directory
+#define ENOEXEC             45  // executable file error
+#define ENOLCK              46  // no locks available
+#define ENOLINK             47  // reserved
+#define ENOMEM              48  // ran out of memory
+#define ENOMSG              49  // no message of desired type
+#define ENOPROTOOPT         50  // protocol not implemented
+#define ENOSPC              51  // ran out of storage
+#define ENOSYS              52  // function not supported
+#define ENOTCONN            53  // socket not connected
+#define ENOTDIR             54  // not a directory nor symlink to directory
+#define ENOTEMPTY           55  // directory not empty
+#define ENOTRECOVERABLE     56  // unrecoverable error
+#define ENOTSOCK            57  // not a socket
+#define ENOTSUP             58  // operation not supported
+#define EOPNOTSUPP          ENOTSUP
+#define ENOTTY              59  // inappropriate I/O
+#define ENXIO               60  // no such device or address
+#define EOVERFLOW           61  // value larger than data type
+#define EOWNERDEAD          62  // previous owner died
+#define EPERM               63  // operation not permitted
+#define EPIPE               64  // broken pipe
+#define EPROTO              65  // protocol error
+#define EPROTONOSUPPORT     66  // protocol not supported
+#define EPROTOTYPE          67  // wrong protocol type
+#define ERANGE              68  // result too large
+#define EROFS               69  // read-only file system
+#define ESPIPE              70  // invalid seek
+#define ESRCH               71  // no such process
+#define ESTALE              72  // reserved
+#define ETIMEDOUT           73  // connection timeout
+#define ETXTBSY             74  // text file busy
+#define EWOULDBLOCK         75  // blocking operation
+#define EXDEV               76  // cross-device link

src/include/kernel/io.h

@@ -0,0 +1,42 @@
+/*
+ * lux - a lightweight unix-like operating system
+ * Omar Elghoul, 2024
+ * 
+ * Core Microkernel
+ */
+
+/* Abstractions for file systems and sockets */
+
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <kernel/sched.h>
+
+#define MAX_IO_DESCRIPTORS      1024    // max files/sockets open per process
+
+// these are special and reserved descriptors
+#define IO_STDIN                0
+#define IO_STDOUT               1
+#define IO_STDERR               2
+
+#define IO_WAITING              3   // only used during setup
+#define IO_FILE                 4
+#define IO_SOCKET               5
+
+/* I/O descriptor flags */
+#define O_NONBLOCK              0x0001
+#define O_NDELAY                O_NONBLOCK
+#define O_CLOEXEC               0x0002
+
+// TODO: decide whether to implement named pipes as files or an independent type
+
+typedef struct IODescriptor {
+    bool valid;
+    int type;
+    uint16_t flags;
+    void *data;                 // file or socket-specific data
+} IODescriptor;
+
+int openIO(void *, void **);
+void closeIO(void *, void *);

src/include/kernel/sched.h

@@ -12,10 +12,10 @@
 #include <stddef.h>
 #include <sys/types.h>
 #include <kernel/syscalls.h>
+#include <kernel/io.h>
 
-// ideal number of context switches per second
 // still not sure of how to decide on this value so it'll probably change
-#define SCHED_SWITCH_RATE       200
+#define SCHED_TIME_SLICE        1       // ms
 
 #define MAX_PID                 99999
 
@@ -25,9 +25,9 @@
 #define THREAD_ZOMBIE           3
 #define THREAD_SLEEP            4
 
-#define PRIORITY_HIGH           0
-#define PRIORITY_NORMAL         1
-#define PRIORITY_LOW            2
+#define PRIORITY_LOW            1
+#define PRIORITY_NORMAL         2
+#define PRIORITY_HIGH           3
 
 typedef struct Thread {
     int status, cpu, priority;
@@ -56,6 +56,9 @@ typedef struct Process {
     char *env;              // environmental variables
     char *command;          // command line with arguments
 
+    struct IODescriptor io[MAX_IO_DESCRIPTORS];
+    int iodCount;
+
     size_t threadCount;
     size_t childrenCount;
 
@@ -81,6 +84,7 @@ void setScheduling(bool);
 void blockThread(Thread *);
 void unblockThread(Thread *);
 Process *getProcessQueue();
+void schedStatus();
 
 pid_t kthreadCreate(void *(*)(void *), void *);
 pid_t processCreate();

src/include/kernel/socket.h

@@ -0,0 +1,75 @@
+/*
+ * lux - a lightweight unix-like operating system
+ * Omar Elghoul, 2024
+ * 
+ * Core Microkernel
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <kernel/sched.h>
+#include <sys/types.h>
+
+/* system-wide limits */
+#define MAX_SOCKETS             (1 << 18)   // 262k
+#define SOCKET_DEFAULT_BACKLOG  1024        // default socket backlog size
+
+/* socket family/domain - only Unix sockets will be implemented in the kernel */
+#define AF_UNIX                 1
+#define AF_LOCAL                AF_UNIX
+
+/* socket type - these will be ignored for local Unix sockets */
+/* the kernel will ensure packets are sent and received in the same order */
+#define SOCK_STREAM             1       // stream-oriented
+#define SOCK_DGRAM              2       // datagram-oriented
+#define SOCK_SEQPACKET          3       // connection-oriented
+
+/* additional socket flags */
+#define SOCK_NONBLOCK           0x100
+#define SOCK_CLOEXEC            0x200
+
+typedef uint16_t sa_family_t;
+typedef size_t socklen_t;
+
+/* generic socket */
+struct sockaddr {
+    sa_family_t sa_family;
+    char sa_data[512];
+};
+
+/* Unix domain socket */
+struct sockaddr_un {
+    sa_family_t sun_family;     // AF_UNIX
+    char sun_path[512];         // filename
+};
+
+/* socket-specific I/O descriptor (see io.h) */
+typedef struct SocketDescriptor {
+    Process *process;
+    struct sockaddr address;
+    bool listener;
+    int type, protocol, backlogMax, backlogCount;
+    int inboundCount, outboundCount;
+    void **inbound, **outbound;
+    size_t *inboundLen, *outboundLen;
+    struct SocketDescriptor **backlog;  // for incoming connections via connect()
+    struct SocketDescriptor *peer;      // for peer-to-peer connections
+} SocketDescriptor;
+
+void socketInit();
+SocketDescriptor *getLocalSocket(const struct sockaddr *, socklen_t);
+void socketLock();
+void socketRelease();
+int socketRegister(SocketDescriptor *);
+
+/* socket system calls */
+int socket(Thread *, int, int, int);
+int connect(Thread *, int, const struct sockaddr *, socklen_t);
+int bind(Thread *, int, const struct sockaddr *, socklen_t);
+int listen(Thread *, int, int);
+int accept(Thread *, int, struct sockaddr *, socklen_t *);
+ssize_t recv(Thread *, int, void *, size_t, int);
+ssize_t send(Thread *, int, const void *, size_t, int);

src/include/kernel/syscalls.h

@@ -11,10 +11,10 @@
 #include <stdbool.h>
 #include <kernel/sched.h>
 
-#define MAX_SYSCALL                     12       // for now
+#define MAX_SYSCALL                     37       // for now
 
 typedef struct SyscallRequest {
-    bool busy, queued;
+    bool busy, queued, unblock;
 
     uint64_t function;
     uint64_t params[4];

src/include/sys/types.h

@@ -22,3 +22,4 @@ typedef uint64_t off_t;
 typedef uint64_t time_t;
 typedef uint16_t blksize_t;
 typedef uint64_t blkcnt_t;
+typedef int64_t ssize_t;

src/io.c

@@ -0,0 +1,60 @@
+/*
+ * lux - a lightweight unix-like operating system
+ * Omar Elghoul, 2024
+ * 
+ * Core Microkernel
+ */
+
+/* Abstractions for file systems and sockets */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <kernel/sched.h>
+#include <kernel/io.h>
+
+/* openIO(): opens an I/O descriptor in a process
+ * params: p - process to open descriptor in
+ * params: iod - destination to store pointer to I/O descriptor structure
+ * returns: I/O descriptor, negative error code on fail
+ */
+
+int openIO(void *pv, void **iodv) {
+    Process *p = (Process *)pv;
+    IODescriptor **iod = (IODescriptor **)iodv;
+
+    if(p->iodCount >= MAX_IO_DESCRIPTORS) return -ESRCH;
+
+    /* randomly allocate descriptors instead of sequential numbering */
+    int desc;
+    do {
+        desc = rand() % MAX_IO_DESCRIPTORS;
+    } while(p->io[desc].valid);
+
+    p->io[desc].valid = true;
+    p->io[desc].type = IO_WAITING;
+    p->io[desc].data = NULL;
+
+    p->iodCount++;
+
+    *iod = &p->io[desc];
+    return desc;
+}
+
+/* closeIO(): closes an I/O descriptor in a process
+ * params: pv - process to close descriptor in
+ * params: iodv - descriptor to close
+ * returns: nothing
+ */
+
+void closeIO(void *pv, void *iodv) {
+    Process *p = (Process *)pv;
+    IODescriptor *iod = (IODescriptor *) iodv;
+
+    if(iod->valid) {
+        iod->valid = false;
+        if(iod->data) free(iod->data);
+        iod->data = NULL;
+
+        p->iodCount--;
+    }
+}