/*-
 * Copyright (c) 1998 John D. Polstra
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/usr.bin/gcore/elfcore.c,v 1.5.2.3 2001/07/11 23:59:11 obrien Exp $
 */

#define _KERNEL_STRUCTURES

#include <sys/param.h>
#include <sys/lock.h>
#include <sys/procfs.h>
#include <machine/elf.h>
#include <vm/vm_param.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "extern.h"

extern ssize_t gcore_seg_limit;
extern int gcore_verbose;

/*
 * Code for generating ELF core dumps.
 */

typedef void (*segment_callback)(vm_map_entry_t, void *);

/* Closure for cb_put_phdr(). */
struct phdr_closure {
        Elf_Phdr *phdr;         /* Program header to fill in */
        Elf_Off offset;         /* Offset of segment in core file */
};

/* Closure for cb_size_segment(). */
struct sseg_closure {
        int count;              /* Count of writable segments. */
        size_t size;            /* Total size of all writable segments. */
};

static void cb_put_phdr(vm_map_entry_t, void *);
static void cb_size_segment(vm_map_entry_t, void *);
static void each_writable_segment(vm_map_entry_t, segment_callback,
    void *closure);
static void elf_corehdr(int fd, pid_t, vm_map_entry_t, int numsegs,
    void *hdr, size_t hdrsize);
static void elf_puthdr(vm_map_entry_t, void *, size_t *,
    const prstatus_t *, const prfpregset_t *, const prpsinfo_t *, int numsegs);
static void elf_putnote(void *dst, size_t *off, const char *name, int type,
    const void *desc, size_t descsz);
static void freemap(vm_map_entry_t);
static void readhdrinfo(pid_t, prstatus_t *, prfpregset_t *, prpsinfo_t *);
static vm_map_entry_t readmap(pid_t);

/*
 * Write an ELF coredump for the given pid to the given fd.
 */
void
elf_coredump(int fd, pid_t pid)
{
        vm_map_entry_t map;
        struct sseg_closure seginfo;
        void *hdr;
        size_t hdrsize;
        char memname[64];
        int memfd;
        Elf_Phdr *php;
        int i;

        /* Get the program's memory map. */
        map = readmap(pid);

        /* Size the program segments. */
        seginfo.count = 0;
        seginfo.size = 0;
        each_writable_segment(map, cb_size_segment, &seginfo);

        /*
         * Calculate the size of the core file header area by making
         * a dry run of generating it.  Nothing is written, but the
         * size is calculated.
         */
        hdrsize = 0;
        elf_puthdr(map, NULL, &hdrsize, NULL, NULL, NULL, seginfo.count);

        /*
         * Allocate memory for building the header, fill it up,
         * and write it out.
         */
        hdr = malloc(hdrsize);
        if ((hdr = malloc(hdrsize)) == NULL)
                errx(1, "out of memory");
        elf_corehdr(fd, pid, map, seginfo.count, hdr, hdrsize);

        /* Write the contents of all of the writable segments. */
        snprintf(memname, sizeof memname, "/proc/%d/mem", pid);
        if ((memfd = open(memname, O_RDONLY)) == -1)
                err(1, "cannot open %s", memname);

        php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
        for (i = 0;  i < seginfo.count;  i++) {
                long nleft = php->p_filesz;

                lseek(memfd, (off_t)php->p_vaddr, SEEK_SET);
                while (nleft > 0) {
                        char buf[65536];
                        ssize_t nwant;
                        ssize_t ngot;

                        nwant = (ssize_t)nleft;
                        if (nwant > sizeof buf)
                                nwant = sizeof buf;
                        ngot = read(memfd, buf, nwant);
                        if (ngot == -1)
                                err(1, "read from %s", memname);
                        if (ngot < nwant)
                                errx(1, "short read from %s:"
                                    " wanted %zd, got %zd\n", memname,
                                    nwant, ngot);
                        ngot = write(fd, buf, nwant);
                        if (ngot == -1)
                                err(1, "write of segment %d failed", i);
                        if (ngot != nwant)
                                errx(1, "short write");
                        nleft -= nwant;
                }
                php++;
        }
        close(memfd);
        free(hdr);
        freemap(map);
}

/*
 * A callback for each_writable_segment() to write out the segment's
 * program header entry.
 */
static void
cb_put_phdr(vm_map_entry_t entry, void *closure)
{
        struct phdr_closure *phc = (struct phdr_closure *)closure;
        Elf_Phdr *phdr = phc->phdr;

        phc->offset = round_page(phc->offset);

        phdr->p_type = PT_LOAD;
        phdr->p_offset = phc->offset;
        phdr->p_vaddr = entry->ba.start;
        phdr->p_paddr = 0;
        phdr->p_filesz = phdr->p_memsz = entry->ba.end - entry->ba.start;
        phdr->p_align = PAGE_SIZE;
        phdr->p_flags = 0;
        if (entry->protection & VM_PROT_READ)
                phdr->p_flags |= PF_R;
        if (entry->protection & VM_PROT_WRITE)
                phdr->p_flags |= PF_W;
        if (entry->protection & VM_PROT_EXECUTE)
                phdr->p_flags |= PF_X;

        phc->offset += phdr->p_filesz;
        phc->phdr++;
}

/*
 * A callback for each_writable_segment() to gather information about
 * the number of segments and their total size.
 */
static void
cb_size_segment(vm_map_entry_t entry, void *closure)
{
        struct sseg_closure *ssc = (struct sseg_closure *)closure;

        ssc->count++;
        ssc->size += entry->ba.end - entry->ba.start;
}

/*
 * For each segment in the given memory map, call the given function
 * with a pointer to the map entry and some arbitrary caller-supplied
 * data.
 */
static void
each_writable_segment(vm_map_entry_t map, segment_callback func, void *closure)
{
        vm_map_entry_t entry;

        for (entry = map; entry; entry = entry->rb_entry.rbe_parent)
                (*func)(entry, closure);
}

/*
 * Write the core file header to the file, including padding up to
 * the page boundary.
 */
static void
elf_corehdr(int fd, pid_t pid, vm_map_entry_t map, int numsegs, void *hdr,
    size_t hdrsize)
{
        size_t off;
        prstatus_t status;
        prfpregset_t fpregset;
        prpsinfo_t psinfo;

        /* Gather the information for the header. */
        readhdrinfo(pid, &status, &fpregset, &psinfo);

        /* Fill in the header. */
        memset(hdr, 0, hdrsize);
        off = 0;
        elf_puthdr(map, hdr, &off, &status, &fpregset, &psinfo, numsegs);

        /* Write it to the core file. */
        if (write(fd, hdr, hdrsize) == -1)
                err(1, "write");
}

/*
 * Generate the ELF coredump header into the buffer at "dst".  "dst" may
 * be NULL, in which case the header is sized but not actually generated.
 */
static void
elf_puthdr(vm_map_entry_t map, void *dst, size_t *off, const prstatus_t *status,
    const prfpregset_t *fpregset, const prpsinfo_t *psinfo, int numsegs)
{
        size_t ehoff;
        size_t phoff;
        size_t noteoff;
        size_t notesz;

        ehoff = *off;
        *off += sizeof(Elf_Ehdr);

        phoff = *off;
        *off += (numsegs + 1) * sizeof(Elf_Phdr);

        noteoff = *off;
        elf_putnote(dst, off, "FreeBSD", NT_PRSTATUS, status,
            sizeof *status);
        elf_putnote(dst, off, "FreeBSD", NT_FPREGSET, fpregset,
            sizeof *fpregset);
        elf_putnote(dst, off, "FreeBSD", NT_PRPSINFO, psinfo,
            sizeof *psinfo);
        notesz = *off - noteoff;

        /* Align up to a page boundary for the program segments. */
        *off = round_page(*off);

        if (dst != NULL) {
                Elf_Ehdr *ehdr;
                Elf_Phdr *phdr;
                struct phdr_closure phc;

                /*
                 * Fill in the ELF header.
                 */
                ehdr = (Elf_Ehdr *)((char *)dst + ehoff);
                ehdr->e_ident[EI_MAG0] = ELFMAG0;
                ehdr->e_ident[EI_MAG1] = ELFMAG1;
                ehdr->e_ident[EI_MAG2] = ELFMAG2;
                ehdr->e_ident[EI_MAG3] = ELFMAG3;
                ehdr->e_ident[EI_CLASS] = ELF_CLASS;
                ehdr->e_ident[EI_DATA] = ELF_DATA;
                ehdr->e_ident[EI_VERSION] = EV_CURRENT;
                ehdr->e_ident[EI_OSABI] = ELFOSABI_NONE;
                ehdr->e_ident[EI_ABIVERSION] = 0;
                ehdr->e_ident[EI_PAD] = 0;
                ehdr->e_type = ET_CORE;
                ehdr->e_machine = ELF_ARCH;
                ehdr->e_version = EV_CURRENT;
                ehdr->e_entry = 0;
                ehdr->e_phoff = phoff;
                ehdr->e_flags = 0;
                ehdr->e_ehsize = sizeof(Elf_Ehdr);
                ehdr->e_phentsize = sizeof(Elf_Phdr);
                ehdr->e_phnum = numsegs + 1;
                ehdr->e_shentsize = sizeof(Elf_Shdr);
                ehdr->e_shnum = 0;
                ehdr->e_shstrndx = SHN_UNDEF;

                /*
                 * Fill in the program header entries.
                 */
                phdr = (Elf_Phdr *)((char *)dst + phoff);

                /* The note segement. */
                phdr->p_type = PT_NOTE;
                phdr->p_offset = noteoff;
                phdr->p_vaddr = 0;
                phdr->p_paddr = 0;
                phdr->p_filesz = notesz;
                phdr->p_memsz = 0;
                phdr->p_flags = 0;
                phdr->p_align = 0;
                phdr++;

                /* All the writable segments from the program. */
                phc.phdr = phdr;
                phc.offset = *off;
                each_writable_segment(map, cb_put_phdr, &phc);
        }
}

/*
 * Emit one note section to "dst", or just size it if "dst" is NULL.
 */
static void
elf_putnote(void *dst, size_t *off, const char *name, int type,
    const void *desc, size_t descsz)
{
        Elf_Note note;

        note.n_namesz = strlen(name) + 1;
        note.n_descsz = descsz;
        note.n_type = type;
        if (dst != NULL)
                bcopy(&note, (char *)dst + *off, sizeof note);
        *off += sizeof note;
        if (dst != NULL)
                bcopy(name, (char *)dst + *off, note.n_namesz);
        *off += roundup2(note.n_namesz, sizeof(Elf_Size));
        if (dst != NULL)
                bcopy(desc, (char *)dst + *off, note.n_descsz);
        *off += roundup2(note.n_descsz, sizeof(Elf_Size));
}

/*
 * Free the memory map.
 */
static void
freemap(vm_map_entry_t map)
{
        while (map != NULL) {
                vm_map_entry_t next = map->rb_entry.rbe_parent;
                free(map);
                map = next;
        }
}

/*
 * Read the process information necessary to fill in the core file's header.
 */
static void
readhdrinfo(pid_t pid, prstatus_t *status, prfpregset_t *fpregset,
    prpsinfo_t *psinfo)
{
        char name[64];
        char line[256];
        int fd;
        int i;
        int n;

        memset(status, 0, sizeof *status);
        status->pr_version = PRSTATUS_VERSION;
        status->pr_statussz = sizeof(prstatus_t);
        status->pr_gregsetsz = sizeof(gregset_t);
        status->pr_fpregsetsz = sizeof(fpregset_t);
        status->pr_osreldate = __DragonFly_version;
        status->pr_pid = pid;

        memset(fpregset, 0, sizeof *fpregset);

        memset(psinfo, 0, sizeof *psinfo);
        psinfo->pr_version = PRPSINFO_VERSION;
        psinfo->pr_psinfosz = sizeof(prpsinfo_t);

        /* Read the general registers. */
        snprintf(name, sizeof name, "/proc/%d/regs", pid);
        if ((fd = open(name, O_RDONLY)) == -1)
                err(1, "cannot open %s", name);
        if ((n = read(fd, &status->pr_reg, sizeof status->pr_reg)) == -1)
                err(1, "read error from %s", name);
        if (n < sizeof status->pr_reg)
                errx(1, "short read from %s: wanted %zu, got %d",
                     name, sizeof(status->pr_reg), n);
        close(fd);

        /* Read the floating point registers. */
        snprintf(name, sizeof name, "/proc/%d/fpregs", pid);
        if ((fd = open(name, O_RDONLY)) == -1)
                err(1, "cannot open %s", name);
        if ((n = read(fd, fpregset, sizeof *fpregset)) == -1)
                err(1, "read error from %s", name);
        if (n < sizeof *fpregset)
                errx(1, "short read from %s: wanted %zu, got %d",
                     name, sizeof(*fpregset), n);
        close(fd);

        /* Read and parse the process status. */
        snprintf(name, sizeof name, "/proc/%d/status", pid);
        if ((fd = open(name, O_RDONLY)) == -1)
                err(1, "cannot open %s", name);
        if ((n = read(fd, line, sizeof line - 1)) == -1)
                err(1, "read error from %s", name);
        if (n > MAXCOMLEN)
                n = MAXCOMLEN;
        for (i = 0;  i < n && line[i] != ' ';  i++)
                psinfo->pr_fname[i] = line[i];
        strncpy(psinfo->pr_psargs, psinfo->pr_fname, PRARGSZ);
        close(fd);
}

/*
 * Read the process's memory map using procfs, and return a list of
 * VM map entries.  Only the non-device read/writable segments are
 * returned.  The map entries in the list aren't fully filled in; only
 * the items we need are present.
 */
static vm_map_entry_t
readmap(pid_t pid)
{
        char mapname[64];
        int mapfd;
        ssize_t mapsize;
        size_t bufsize;
        char *mapbuf;
        int pos;
        vm_map_entry_t map;
        vm_map_entry_t *linkp;

        snprintf(mapname, sizeof mapname, "/proc/%d/map", pid);
        if ((mapfd = open(mapname, O_RDONLY)) == -1)
                err(1, "cannot open %s", mapname);

        /*
         * Procfs requires (for consistency) that the entire memory map
         * be read with a single read() call.  Start with a reasonbly sized
         * buffer, and double it until it is big enough.
         */
        bufsize = 65536;
        mapbuf = NULL;
        for ( ; ; ) {
                if ((mapbuf = realloc(mapbuf, bufsize + 1)) == NULL)
                        errx(1, "out of memory");
                mapsize = read(mapfd, mapbuf, bufsize);
                if ((mapsize != -1 || errno != EFBIG) && mapsize != bufsize) {
                        break;
                }
                bufsize *= 2;
                /* This lseek shouldn't be necessary, but it is. */
                lseek(mapfd, (off_t)0, SEEK_SET);
        }
        if (mapsize == -1)
                err(1, "read error from %s", mapname);
        if (mapsize == 0)
                errx(1, "empty map file %s", mapname);
        mapbuf[mapsize] = 0;
        close(mapfd);

        pos = 0;
        map = NULL;
        linkp = &map;
        while (pos < mapsize) {
                vm_map_entry_t ent;
                vm_offset_t start;
                vm_offset_t end;
                char prot[4];
                char type[16];
                int n;
                int len;
                int skipme = 0;

                len = 0;
                n = sscanf(mapbuf + pos, "%lx %lx %*d %*d %*x %3[-rwx]"
                    " %*d %*d %*x %*s %*s %15s %*s%*[\n]%n",
                    &start, &end, prot, type, &len);
                if (n != 4)
                        errx(1, "ill-formed line in %s: '%s'",
                            mapname, mapbuf);
                pos += len;

                /* Ignore segments of the wrong kind, and unwritable ones */
                if (gcore_seg_limit >= 0 && end - start > gcore_seg_limit) {
                        skipme = 1;
                }
                if (strncmp(prot, "rw", 2) != 0 ||
                    (strcmp(type, "default") != 0 &&
                    strcmp(type, "vnode") != 0 &&
                    strcmp(type, "swap") != 0)) {
                        skipme = 2;
                }
                if (gcore_verbose || skipme == 1)
                        printf("%016lx-%016lx (%ldM) %s,%s",
                               start, end,
                                (end - start) / (1024 * 1024),
                                prot, type);
                if (skipme) {
                        if (skipme == 1)
                                printf(" (ignored - seglimit)\n");
                        else if (gcore_verbose)
                                printf(" (ignored)\n");
                        continue;
                }
                if (gcore_verbose)
                        printf("\n");

                if ((ent = (vm_map_entry_t)calloc(1, sizeof *ent)) == NULL)
                        errx(1, "out of memory");
                ent->ba.start = start;
                ent->ba.end = end;
                ent->protection = VM_PROT_READ | VM_PROT_WRITE;
                if (prot[2] == 'x')
                    ent->protection |= VM_PROT_EXECUTE;

                *linkp = ent;
                linkp = &ent->rb_entry.rbe_parent;
        }
        free(mapbuf);
        return map;
}