// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <elf.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <zircon/driver/binding.h>
#include <zircon/types.h>

#include <driver-info/driver-info.h>

typedef zx_status_t (*note_func_t)(void* note, size_t sz, void* cookie);

typedef Elf64_Ehdr elfhdr;
typedef Elf64_Phdr elfphdr;
typedef Elf64_Nhdr notehdr;

static zx_status_t find_note(const char* name, size_t nlen, uint32_t type, void* data, size_t size,
                             note_func_t func, void* cookie) {
  while (size >= sizeof(notehdr)) {
    const notehdr* hdr = data;
    uint32_t nsz = (hdr->n_namesz + 3) & (~3);
    if (nsz > (size - sizeof(notehdr))) {
      return ZX_ERR_INTERNAL;
    }
    size_t hsz = sizeof(notehdr) + nsz;
    data += hsz;
    size -= hsz;

    uint32_t dsz = (hdr->n_descsz + 3) & (~3);
    if (dsz > size) {
      return ZX_ERR_INTERNAL;
    }

    if ((hdr->n_type == type) && (hdr->n_namesz == nlen) && (memcmp(name, hdr + 1, nlen) == 0)) {
      return func(data - hsz, hdr->n_descsz + hsz, cookie);
    }

    data += dsz;
    size -= dsz;
  }
  return ZX_ERR_NOT_FOUND;
}

static zx_status_t for_each_note(void* obj, di_read_func_t diread, const char* name, uint32_t type,
                                 void* data, size_t dsize, note_func_t func, void* cookie) {
  size_t nlen = strlen(name) + 1;
  elfphdr ph[64];
  elfhdr eh;
  if (diread(obj, &eh, sizeof(eh), 0) != ZX_OK) {
    printf("for_each_note: pread(eh) failed\n");
    return ZX_ERR_IO;
  }
  if (memcmp(&eh, ELFMAG, 4) || (eh.e_ehsize != sizeof(elfhdr)) ||
      (eh.e_phentsize != sizeof(elfphdr))) {
    printf("for_each_note: bad elf magic\n");
    return ZX_ERR_INTERNAL;
  }
  size_t sz = sizeof(elfphdr) * eh.e_phnum;
  if (sz > sizeof(ph)) {
    printf("for_each_note: too many phdrs\n");
    return ZX_ERR_INTERNAL;
  }
  if (diread(obj, ph, sz, eh.e_phoff) != ZX_OK) {
    printf("for_each_note: pread(sz,eh.e_phoff) failed\n");
    return ZX_ERR_IO;
  }
  for (int i = 0; i < eh.e_phnum; i++) {
    if ((ph[i].p_type != PT_NOTE) || (ph[i].p_filesz > dsize)) {
      continue;
    }
    if (diread(obj, data, ph[i].p_filesz, ph[i].p_offset) != ZX_OK) {
      printf("for_each_note: pread(ph[i]) failed\n");
      return ZX_ERR_IO;
    }
    int r = find_note(name, nlen, type, data, ph[i].p_filesz, func, cookie);
    if (r == ZX_OK) {
      return r;
    }
  }
  return ZX_ERR_NOT_FOUND;
}

typedef struct {
  void* cookie;
  di_info_func_t func;
} context;

static zx_status_t callback(void* note, size_t sz, void* _ctx) {
  context* ctx = _ctx;
  zircon_driver_note_t* dn = note;
  if (sz < sizeof(zircon_driver_note_t)) {
    return ZX_ERR_INTERNAL;
  }
  size_t max = (sz - sizeof(zircon_driver_note_t)) / sizeof(zx_bind_inst_t);
  if (dn->payload.bindcount > max) {
    return ZX_ERR_INTERNAL;
  }
  const zx_bind_inst_t* binding = (const void*)(&dn->payload + 1);
  ctx->func(&dn->payload, binding, ctx->cookie);
  return ZX_OK;
}

static zx_status_t di_pread(void* obj, void* data, size_t len, size_t off) {
  if (pread(*((int*)obj), data, len, off) == (ssize_t)len) {
    return ZX_OK;
  } else {
    return ZX_ERR_IO;
  }
}

zx_status_t di_read_driver_info_etc(void* obj, di_read_func_t rfunc, void* cookie,
                                    di_info_func_t func) {
  context ctx = {
      .cookie = cookie,
      .func = func,
  };
  uint8_t data[4096];
  return for_each_note(obj, rfunc, ZIRCON_NOTE_NAME, ZIRCON_NOTE_DRIVER, data, sizeof(data),
                       callback, &ctx);
}

zx_status_t di_read_driver_info(int fd, void* cookie, di_info_func_t func) {
  context ctx = {
      .cookie = cookie,
      .func = func,
  };
  uint8_t data[4096];
  return for_each_note(&fd, di_pread, ZIRCON_NOTE_NAME, ZIRCON_NOTE_DRIVER, data, sizeof(data),
                       callback, &ctx);
}

const char* di_bind_param_name(uint32_t param_num) {
  switch (param_num) {
    case BIND_FLAGS:
      return "Flags";
    case BIND_PROTOCOL:
      return "Protocol";
    case BIND_AUTOBIND:
      return "Autobind";
    case BIND_PCI_VID:
      return "PCI.VID";
    case BIND_PCI_DID:
      return "PCI.DID";
    case BIND_PCI_CLASS:
      return "PCI.Class";
    case BIND_PCI_SUBCLASS:
      return "PCI.Subclass";
    case BIND_PCI_INTERFACE:
      return "PCI.Interface";
    case BIND_PCI_REVISION:
      return "PCI.Revision";
    case BIND_TOPO_PCI:
      return "Topology.PCI";
    case BIND_USB_VID:
      return "USB.VID";
    case BIND_USB_PID:
      return "USB.PID";
    case BIND_USB_CLASS:
      return "USB.Class";
    case BIND_USB_SUBCLASS:
      return "USB.Subclass";
    case BIND_USB_PROTOCOL:
      return "USB.Protocol";
    case BIND_PLATFORM_DEV_VID:
      return "PlatDev.VID";
    case BIND_PLATFORM_DEV_PID:
      return "PlatDev.PID";
    case BIND_PLATFORM_DEV_DID:
      return "PlatDev.DID";
    case BIND_ACPI_HID_0_3:
      return "ACPI.HID[0-3]";
    case BIND_ACPI_HID_4_7:
      return "ACPI.HID[4-7]";
    case BIND_IHDA_CODEC_VID:
      return "IHDA.Codec.VID";
    case BIND_IHDA_CODEC_DID:
      return "IHDA.Codec.DID";
    case BIND_IHDA_CODEC_MAJOR_REV:
      return "IHDACodec.MajorRev";
    case BIND_IHDA_CODEC_MINOR_REV:
      return "IHDACodec.MinorRev";
    case BIND_IHDA_CODEC_VENDOR_REV:
      return "IHDACodec.VendorRev";
    case BIND_IHDA_CODEC_VENDOR_STEP:
      return "IHDACodec.VendorStep";
    default:
      return NULL;
  }
}

void di_dump_bind_inst(const zx_bind_inst_t* b, char* buf, size_t buf_len) {
  if (!b || !buf || !buf_len) {
    return;
  }

  uint32_t cc = BINDINST_CC(b->op);
  uint32_t op = BINDINST_OP(b->op);
  uint32_t pa = BINDINST_PA(b->op);
  uint32_t pb = BINDINST_PB(b->op);
  size_t off = 0;
  buf[0] = 0;

  switch (op) {
    case OP_ABORT:
    case OP_MATCH:
    case OP_GOTO:
      break;
    case OP_LABEL:
      snprintf(buf + off, buf_len - off, "L.%u:", pa);
      return;
    default:
      snprintf(buf + off, buf_len - off, "Unknown Op 0x%1x [0x%08x, 0x%08x]", op, b->op, b->arg);
      return;
  }

  off += snprintf(buf + off, buf_len - off, "if (");
  if (cc == COND_AL) {
    off += snprintf(buf + off, buf_len - off, "true");
  } else {
    const char* pb_name = di_bind_param_name(pb);
    if (pb_name) {
      off += snprintf(buf + off, buf_len - off, "%s", pb_name);
    } else {
      off += snprintf(buf + off, buf_len - off, "P.%04x", pb);
    }

    switch (cc) {
      case COND_EQ:
        off += snprintf(buf + off, buf_len - off, " == 0x%08x", b->arg);
        break;
      case COND_NE:
        off += snprintf(buf + off, buf_len - off, " != 0x%08x", b->arg);
        break;
      case COND_GT:
        off += snprintf(buf + off, buf_len - off, " > 0x%08x", b->arg);
        break;
      case COND_LT:
        off += snprintf(buf + off, buf_len - off, " < 0x%08x", b->arg);
        break;
      case COND_GE:
        off += snprintf(buf + off, buf_len - off, " >= 0x%08x", b->arg);
        break;
      case COND_LE:
        off += snprintf(buf + off, buf_len - off, " <= 0x%08x", b->arg);
        break;
      default:
        off += snprintf(buf + off, buf_len - off, " ?(0x%x) 0x%08x", cc, b->arg);
        break;
    }
  }
  off += snprintf(buf + off, buf_len - off, ") ");

  switch (op) {
    case OP_ABORT:
      off += snprintf(buf + off, buf_len - off, "return no-match;");
      break;
    case OP_MATCH:
      off += snprintf(buf + off, buf_len - off, "return match;");
      break;
    case OP_GOTO:
      off += snprintf(buf + off, buf_len - off, "goto L.%u;", b->arg);
      break;
  }
}