I'm using curl in my code and running through Makefile. but while running with "make" command its giving error like "curl/curl.h: No such file or directory". Here below is my makefile content. ` CXX = /home/directory/Documents/xyz/l4t-gcc/bin/aarch64-buildroot-linux-gnu-cc path = /home/directory/Documents/xyz/l4t-gcc/bin/ CFLAGS = -Wall #INCLUDE = -I/usr/local/include -I/usr/include -Iinclude #LDFLAGS = -L/usr/local/lib -I/usr/lib LDLIBS = -lcurl SOURCES = src/sms_wrapper.c src/twilio.c OUT = bin/sms_wrapper all: build build: $(SOURCES) $(CXX) -o $(OUT) $(CFLAGS) $(SOURCES) $(LDLIBS) clean: rm -rf bin/sms_wrapper ` I installed curl and added all things in Makefile which is needed for curl library. Does anyone have any suggestions or idea for resolving this thing !

So I am designing a feature to redirect log file if there are multiple processes of this very program are running. I guess this requires me to somehow get to know whether there exists yet unfinished same program(executable?). I wonder is this achievable within user mode? How?

Assume the following C snippet showing a piece of error handling:

#include 
#include 
…
int main(int argc, char argv*[]) {
  int retval=0;
  …
  if(3!=argc) { /* wrong number of arguments */
    retval |= EX_USAGE;
    const int fprintf_retval = fprintf(stderr, "Bad syntax.\n");
    if (0>=fprintf_retval) retval |= … Hmm …  ;
  }
  …
  return retval;
}

Which error constant from sysexits.h should be placed instead of “… Hmm …”? We can say EX_OSERR (a failure to print an error message shows that something is off, though not necessarily deep in the operating system), or EX_IOERR (it's an output error, though not necessarily into a file), or EX_SOFTWARE (fairly general, but the reason for a failure to print an error typically lies outside the C program, and the error might relate to the operating system). Based only on the comments in sysexits.h, neither of the three constants fits perfectly. So what's the convention? EDIT: In the scope of this question, we assume that the programmer does want to discern between certain kinds of errors via the exit code, and that more than one error can occur.

The 'gmtime()' standard library function returns a struct that has days numbered 1-31, but months numbered 0-11. Why is that? Presumably there is some historic reason?

I am writing a simple shell program. When I use /usr/bin/which with my shell in mac osx and ubuntu, it acts normally. When I use the exact same command on Red Hat Enterprise Linux Client release 6.3 (Santiago), I get this error: "which: no ANYCOMMANDHERE in ((null))". Is there any intuition for this? I can't even find what the error means (Let me know if showing my source will help). **EDIT: My path is (from inside the shell):** $ echo $PATH /usr/lib64/qt-3.3/bin:/usr/local/bin:/bin:/usr/bin Thanks, Jon

Are there any lists compiled that provide a list of linux system calls used per function in a standard glibc build? For example, free() requires mmap, munmap, mprotect, prlimit64, and brk. If necessary I can figure this out by grepping the source code or some strace wizardry, but I don't want to reinvent the wheel. I've been searching the web for about a week with no avail, mostly just turning up info on system call wrappers. I am aware that officially there is no such certainty, but I know from practical experience that this info changes for most functions very rarely. I asked this on Stack Overflow, but this forum seems more appropriate, since I am looking for documentation (which may or may not exist). Thanks

I wrote a program to get the details of hard disk drive using HDIO_ ioctl calls. For writing program, I'm referring Documentation/ioctl/hdio.txt in kernel source(2.6.32). Here is my main part of code: fd = open("/dev/sda", O_RDONLY); // validated fd. retval = ioctl(fd, HDIO_GET_IDENTITY, &driveid); if(retval < 0) { perror("ioctl(HDIO_GET_IDENTITY)"); exit(3); } When I run(as root) the above code, I got below error: ioctl(HDIO_GET_IDENTITY): Invalid argument What is the wrong in the program? Why I'm getting error? **Additional Info**: OS: CentOS-6.5, kernel version: 2.6.32, IA:x86_64 (running on VMware). Result of hdparm -i /dev/sda is SG_IO: bad/missing sense data, sb[]: 70 00 05 00 00 00 00 0a 00 00 00 00 20 00 00 c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 HDIO_GET_IDENTITY failed: Invalid argument

I’m trying to write a C wrapper to run a bash process. The goal of this wrapper is to apply a seccomp policy to restrict certain syscalls. Here is the code:

#define _GNU_SOURCE
#include 
#include 
#include 
#include 
#include 
#include 
#include 

// Function to apply seccomp filter
void apply_seccomp_filter() {
    scmp_filter_ctx ctx;

    // Initialize seccomp context with default allow policy
    ctx = seccomp_init(SCMP_ACT_ALLOW);
    if (ctx == NULL) {
        perror("seccomp_init");
        exit(EXIT_FAILURE);
    }

    // Block finit_module syscall
    if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(finit_module), 0) < 0) {
        perror("seccomp_rule_add: finit_module");
        seccomp_release(ctx);
        exit(EXIT_FAILURE);
    }

    // Load the filter
    if (seccomp_load(ctx) < 0) {
        perror("seccomp_load");
        seccomp_release(ctx);
        exit(EXIT_FAILURE);
    }

    seccomp_release(ctx);
}

int main() {
    apply_seccomp_filter();
    execl("/bin/bash", "bash", NULL);
    perror("execl");
    return EXIT_FAILURE;
}

The code works fine to block the syscall, but when I try to run sudo, I get this message:

sudo: The "no new privileges" flag is set, which prevents sudo from running as root.
sudo: If sudo is running in a container, you may need to adjust the container configuration to disable the flag.

Do you know how to disable this flag? All the answers I find online are related to containers like Docker, but that’s not my case. Thanks in advance for your help!

We are two FreeBSD lovers and a stubborn system administrators. We are trying to project a phone based on FreeBSD for several months. Emanuel Vadot and Jesper Schmitz Mouridsen have enabled the panfrost driver already,but on the rockpro RK3399,but for my phone I've chosen the smaller Radxa board. These are their github with their kernel patches code : https://github.com/evadot/drm-subtree https://github.com/jsm222/drm-subtree We are trying to see if the panfrost driver worked on that board. Unfortunately,it seems that some code is missing,such as the vop2. Anyway,I want to show you the error that we get : We would have some clarification about what's missing,what should be fixed in the code. Eventually I could hire a FreeBSD kernel developer to produce the patch needed to enable it on the Radxa board. It makes no sense to run FreeBSD on a phone without being able to use its GPU / MALI / acceleration. We need a vop2 driver. Linux driver has 5000 lines of code and supports all of the vop2 variants .compatible = "rockchip,rk3566-vop", .compatible = "rockchip,rk3568-vop", .compatible = "rockchip,rk3576-vop", .compatible = "rockchip,rk3588-vop", this 5k lines do not include support for the rk3588 newer hdmi variants but lets ignore that for now and assume that current hdmi code will work for rk356x ; also from what i've seen the current linux vop2 code is for a newer release of drm than what evadot's code uses so the api is slightly different. Please enlighten us with some lucid considerations. Someone wants help us ? Thanks.

Trying to move a window by grip-able button. On 2 other window managers, and no manager it works fine. Windows move anywhere you want pass display edge bounds. On GNOME Shell and Mutter(Gala) the window is confined to the desktop view with no part of it allowed past display edges. On Compiz I use _NET_WM_MOVERESIZE, other 2 are grab_pointer. The mutter variants won't work using _NET_WM_MOVERESIZE which is fine, but I can't figure out what property to set on the window to allow normal configure messages to get past display limits. Hint as to which it is would be appreciated, kinda would like to support the variant. Need a window_property_set or client message to root to be able to use configure_window. Using code:

#if USE_XLIB
  XMoveWindow(display, motion->event, values, values);
#else
  xcb_configure_window(session->connection, motion->event,
               XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y, values);
#endif

This will only allow movement to the confines of 'maximize' window display. Moving left, negative x values get converted by GNOME to 0. Moving toward bottom, any value greater than window.y + window.height gets converted to display height - taskbar height - window height by GNOME. Verified by values received on configure notify. Do I need to delete a _NET_WM_STRUT property on my window or root window to use? Looking at gdk3 code they use the Xlib variant of code. **Solved**\ Problem is issue that GNOME only supports move of window correctly through their toolkit. It appears to lack proper support of both EWMH and ICCCM. Workaround is to use override-redirect, taking away its ability to mess with configure message.

If I open a fifo for reading+writing in blocking mode: fd = open("foo", "O_RDWR"); Then it blocks until someone on the other end opens it for either reading or writing. But how do I know which? if(???) { read(fd, .......); } else { write(fd, ......); } close(fd); (I need that close, because if I am writing I need to send an EOF to the other end. And any writer will send a single line through and close, so I also need to close if I read.) What do I put instead of the ??? to figure out what the other end did? Is non-blocking and select() my only option? Is there a way to inspect fd and see if it's ready for reading or writing?

I’m trying to run a C program, but every time I try to run it I get this message: error while loading shared libraries: libpcap.so.0.8: cannot open shared object file: No such file or directory I've re-installed libpcap; I've installed gcc and g++; I’ve updated it and I’m lost. I’m not sure what else I can do. Could anyone help out?

I am testing FTRACE in Linux VM (ubuntu 24.04) the kernel is Linux VirtualBox 6.11.0-26-generic. I wrote a kernel module to register a hook (probe) to kernel tracepoint of signal_generate, here is the code.

include 
#include 
#include 

static void trace_signal_generate_handler(void *ignore, int sig, struct kernel_siginfo *info,
                 struct task_struct *task, int type, int result)
{
    printk("Signal %d generated for task %s (PID=%d), type=%d\n",
           sig, task->comm, task->pid, type);
}

static int __init my_module_init(void) {
    int ret;

    ret = register_trace_signal_generate(trace_signal_generate_handler, NULL);
    if (ret) {
        pr_err("Failed to register tracepoint: %d\n", ret);
        return ret;
    }

    return 0;
}

static void __exit my_module_exit(void) {
    unregister_trace_signal_generate(trace_signal_generate_handler, NULL);
    tracepoint_synchronize_unregister();
}

module_init(my_module_init);
module_exit(my_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("wangt13");
MODULE_DESCRIPTION("Signal Generate Tracepoint Hook Example");

When I compiled this module, I hit following error.

make: Entering directory '/usr/src/linux-headers-6.11.0-26-generic'
warning: the compiler differs from the one used to build the kernel
  The kernel was built by: x86_64-linux-gnu-gcc-13 (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
  You are using:           gcc-13 (Ubuntu 13.2.0-23ubuntu4) 13.2.0
  MODPOST /home/wangt/develop/kermod/Module.symvers
ERROR: modpost: "__tracepoint_signal_generate" [/home/wangt/develop/kermod/tracep_reg.ko] undefined!
make: *** [scripts/Makefile.modpost:145: /home/wangt/develop/kermod/Module.symvers] Error 1
make: *** [/usr/src/linux-headers-6.11.0-26-generic/Makefile:1879: modpost] Error 2
make: *** [Makefile:224: __sub-make] Error 2

I checked the /usr/src/linux-headers-6.11.0-26-generic/include/trace/events/signal.h, and found it is defined there.

36 /**
 37  * signal_generate - called when a signal is generated
 38  * @sig: signal number
 39  * @info: pointer to struct siginfo
 40  * @task: pointer to struct task_struct
 41  * @group: shared or private
 42  * @result: TRACE_SIGNAL_*
 43  *
 44  * Current process sends a 'sig' signal to 'task' process with
 45  * 'info' siginfo. If 'info' is SEND_SIG_NOINFO or SEND_SIG_PRIV,
 46  * 'info' is not a pointer and you can't access its field. Instead,
 47  * SEND_SIG_NOINFO means that si_code is SI_USER, and SEND_SIG_PRIV
 48  * means that si_code is SI_KERNEL.
 49  */
 50 TRACE_EVENT(signal_generate,
 51 
 52     TP_PROTO(int sig, struct kernel_siginfo *info, struct task_struct *task,
 53             int group, int result),
 54 
 55     TP_ARGS(sig, info, task, group, result),
 56 
 57     TP_STRUCT__entry(
 58         __field(    int,    sig         )
 59         __field(    int,    errno           )
 60         __field(    int,    code            )
 61         __array(    char,   comm,   TASK_COMM_LEN   )
 62         __field(    pid_t,  pid         )
 63         __field(    int,    group           )
 64         __field(    int,    result          )
 65     ),
.......

I don't know why there was the error in module compiling. I tried to hook another kernel tracepoint of kmalloc as follows,

ret = register_trace_kmalloc(probe_kmalloc, NULL);

and it was compiled and loaded without error. So how to fix the error of hooking probe to tracepoint of signal_generate, and what is the right way to hook my probe to the tracepoint of signal_generate from within kernel module?

According to *The Open Group Base Specifications Issue 8*, on the rationale of the

()

and

()

functions: > The purpose of the openat() function is to enable opening files in directories other than the current working directory without exposure to race conditions. Any part of the path of a file could be changed in parallel to a call to open(), resulting in unspecified behavior. By opening a file descriptor for the target directory and using the openat() function it can be guaranteed that the opened file is located relative to the desired directory. This wording implies that **any use of

()

with a pathname that doesn't refer to a file in the current working directory is potentially subject to race conditions, even if the path is an absolute constant like

/dev/null

.** While the string literal is immutable, the underlying path components (

/

,

,

) can be altered by another process between resolution steps, leading to unintended behavior or security issues. For example: #define _POSIX_C_SOURCE 202405L #include #include int main(void) { int fd = open("/dev/null", O_RDONLY); if (fd == -1) { return 1; } ... (void) close(fd); return 0; } So the only safe way to open it would be: #define _POSIX_C_SOURCE 202405L #include #include int main(void) { int rootfd = open("/", O_SEARCH); if (rootfd == -1) { return 1; } int devfd = openat(rootfd, "dev", O_SEARCH | O_DIRECTORY); if (devfd == -1) { (void) close(rootfd); return 1; } int nullfd = openat(devfd, "null", O_RDONLY); if (nullfd == -1) { (void) close(devfd); (void) close(rootfd); return 1; } ... (void) close(nullfd); (void) close(devfd); (void) close(rootfd); return 0; } But the path used is a constant character literal that wasn't obtained from another function. I understand how a race condition could occur if there were a time window between retrieving the path and actually opening it, but not in this case. Doesn't my

()

example just replicate what the kernel already does internally during path resolution when using

()

with an absolute path? **Note:** I used

/dev/null

because it's guaranteed to exist, but my question applies to any path that refers to any file or directory in the filesystem.

If you have a process that is waiting for user-input from the stdin scope, then how can you supply that user-input from a second terminal ? Specifically, if I run the c-program while(1){ fgets(string, len, stdin); string[strlen(string)-1] = 0; if(strcmp("Stop", string) == 0){ printf("Gotcha"); return 1; } } then how can I supply the string "Stop" to stdin of that process from another process, such that the first process will stop (and print "Gotcha") ? I've tried to run the c-program in terminal 'pts/0' and open a new terminal ('pts/1') with commands: $ echo "Stop" > /proc//fd/0 $ echo "Stop" > /dev/pts/0 where pid is the process id. The "Stop"-command is "repeated" in the first shell, but the process does not receive it.

I'm trying to compile a [Buildroot](https://bellard.org/tinyemu/buildroot-riscv-2018-10-20.tar.gz) image using a preconfigured builtin _defconfig file... More specific the riscv64_xwin_defconfig which is a simple setup for a riscv64 image with Xorg builtin. Since it's a rather old build i'm doing this inside a Fedora 23 Docker container which has gcc version 5.3.1, i don't think this is a problem since i can successfully build the non-Xwin riscv64 defconfig just fine The problem resides when the Makefile tries to build the specific package "eudev-3.2" Here is the config.log:

configure:3158: $? = 1
configure:3178: checking whether the C compiler works
configure:3200: /home/buildroot-riscv-2018-10-20/output/host/usr/bin/riscv64-buildroot-linux-gnu-gcc -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Os  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  conftest.c -lrt >&5
/home/buildroot-riscv-2018-10-20/output/host/usr/lib/gcc/riscv64-buildroot-linux-gnu/7.3.0/../../../../riscv64-buildroot-linux-gnu/bin/ld: warning: libpthread.so.0, needed by /home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so, not found (try using -rpath or -rpath-link)
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `__pthread_barrier_wait@GLIBC_PRIVATE'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `pthread_attr_setstacksize@GLIBC_2.27'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `__pthread_barrier_init@GLIBC_PRIVATE'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `__pthread_unwind@GLIBC_PRIVATE'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `pthread_create@GLIBC_2.27'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `pthread_sigmask@GLIBC_2.27'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `pthread_once@GLIBC_2.27'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `__shm_directory@GLIBC_PRIVATE'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `pthread_detach@GLIBC_2.27'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `pthread_cancel@GLIBC_2.27'
/home/buildroot-riscv-2018-10-20/output/host/usr/riscv64-buildroot-linux-gnu/sysroot/usr/lib64/lp64d/librt.so: undefined reference to `__pthread_get_minstack@GLIBC_PRIVATE'
collect2: error: ld returned 1 exit status

I am working on a process that forks several times. To debug it, I am using a debug file for which I open a fd and which stays the same for all child forks. Then I have a function print_debug, that will print to that fd. Now when the main process and the childs are printing at the same time, the output is intertwined in the debug file. I tried to solve that via a flock(fd, LOCK_EX), but that seems to have no effect. Here is an excerpt from the print_debug function:

void	print_debug(int fd, char *msg)
{
	
	flock(fd, LOCK_EX);
	print_debug2("... LOCK ACQUIRED ...");
    
    ... printing msg ...
    flock(fd, LOCK_UN);
}

Now when several forks print at the same time, the output looks like this:

--12692-- ... LOCK ACQUIRED ...
--12692-- fork no wait with fd_in 4, fd_out 1 and fd_close
----121269694-2-- - ..... . LOLOCKCK A ACQCQUIUIRERED D .....
.
----121269694-2-- - exriecghutt e sitrdeee o
f pipe started
--12694---- 12.69..2- - LO..CK.  ALOCQCUIK RACED Q..UI.
RE--D 12..69.4-
- --fd12 69ou2-t-  ifs orck urwreaintt
ly: 1
----121269692-4-- - ...... L LOCOCK K ACACQUQUIRIREDED . .....

----121269692-4-- - fofdrk o nuto  owan itcm wdit ch atfd i_is n cu0,rr fend_tlouy:t  15 
and fd_close
--126--9412--69 .6-..-  L..OC. K LOACCKQU AICQREUD IR..ED. .
.--.
12--69124-69- 6-er- rnexo ec2
ute tree
--1269--412--69 6-..- . ..LO.CK  ALOCCKQU IRACEQUDIR ED.. ..
.--.
12--6129694-6- --c fmdd_e oxutec iuts edcu rrfrenomtl y:ex ec5

Clearly, the printing of "lock acquired" overlap. I also controlled the return value of flock, which is always 0 (success). Does flock work in a situation like this? Why do I still have the issues of garbled messages in the log file?

We have a requirement for UDP multicasting in our project using Linux 4.1 kernel with static ip address. Basic UDP multicasting by the use of the sendto function to send data works fine with device static ip 10.13.204.100; the issue comes when I change the ip address of the device to 10.13.204.101 or to any other ip in the same series, the udp multicasting starts showing the error: sendto: network unreachable The UDP has been initialized by the following function: int udp_init() { char multicastTTL = 10; // Create UDP socket: memset(&socket_desc, 0, sizeof(socket_desc)); socket_desc = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); if (socket_desc %d\nsocket_desc==>%d\n", udp_socket_fd, socket_desc); /* Set the TTL (time to live/hop count) for the send */ // if (setsockopt(socket_desc, IPPROTO_IP, IP_MULTICAST_TTL, &multicastTTL, sizeof(multicastTTL)) %s:%d\n", __FILE__, __FUNCTION__, __LINE__); return 1; } } Once the ip has been changed, the UDP socket is closed by the instruction: close(socket_desc) Once again the udp_init function (showed above) is used to initialize the UDP socket and then it is used the sendto function to transmit the data but this causes the error:

sendto:network unreachable

thanks in advance

I am trying to understand what happens when a file, which has been mapped into memory by the mmap system call, is subsequently written to by other processes. I have mmaped memory with PROT_READ protection in "process A". If I close the underlying file descriptor in process A, and another process later writes to that file (not using mmap; just a simple redirection of stdout to the file using > in the shell), is the mmaped memory in the address space of process A affected? Given that the pages are read-only, I would expect them not to change. However, process A is being terminated by SIGBUS signals as a result of invalid memory accesses (Non-existent physical address at address 0x[...]) when trying to parse the mapped memory. I am suspecting that this is stemming from writes to the backing file by other processes. Would setting MAP_PRIVATE be sufficient to completely protect this memory from other processes?

I am creating named pipes in Ubuntu 18 and 16 environments in C language using gcc as compiler (mkfifo() and open()). One of the things I noticed that the named pipes remain in the filesystem after the process ends. My process is a endless process that runs in a while(1) loop because of my requirements and the only way to exit is ctrl-c or the kill command in linux. I might add a ctrl-c signal to properly handle these situations but this is not the question. Given that the named pipe remains in the filesystem (for example /tmp/named_pipe1), do I need to check if the named pipe exists in the filesystem and delete it in the beginning of the process (because the file persists in the system), or is it redundant because even the file stays in the filesystem, it's buffer is deleted and I can use it like a new fresh fifo ? Because I don't want the fifo buffers to be mixed when I ctrl-c exit the previous run of the code and start the new one. I require an empty buffer when I restart the code. **Note:** The system is not restarted between the runs of the process. Just the process is re-run. Thanks in advance.